Fix (Http)WebRequest (Begin|End)GetResponse samples

[antonfirsov]

These samples were not handling the asyncResult.CompletedSynchronously == true case correctly: changing the sample code to use smaller buffer leads to stack overflow because of recursion on synchronous completions.

Besides the fix there the PR adds some consolidation:

• Cleanup and (somewhat) modernize the sample code
• Remove the Timer-based custom timeout implementation, use WebRequest.Timeout instead
• Collapse various samples into one sample
  • Unifiy the HttpWebRequest and WebRequest samples since they are practically identical
  • Delete CPP and VB samples given we don't have the capacity and the intention to maintain them.

Fixes #8662

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/ncl

[learn-build-service-prod]

Learn Build status updates of commit efe60c7:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/cpp/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/CPP/begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/cpp/VS_Snippets_Remoting/WebRequest_BeginGetResponse/CPP/webrequest_begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/HttpWebRequest/Abort/begingetresponse.cs	✅Succeeded	View
snippets/csharp/System.Net/HttpWebRequest/Abort/Project.csproj	✅Succeeded
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/httpwebrequest_begingetresponse.cs	✅Succeeded
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/Project.csproj	✅Succeeded
snippets/csharp/System.Net/WebRequest/BeginGetResponse/Project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/WebRequest/BeginGetResponse/webrequest_begingetresponse.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/HttpWebRequest_BeginGetResponse/VB/httpwebrequest_begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/VB/begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
xml/System.Net/HttpWebRequest.xml	✅Succeeded	View
xml/System.Net/WebRequest.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit b3b4b42:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/cpp/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/CPP/begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/cpp/VS_Snippets_Remoting/WebRequest_BeginGetResponse/CPP/webrequest_begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/HttpWebRequest/Abort/begingetresponse.cs	✅Succeeded	View
snippets/csharp/System.Net/HttpWebRequest/Abort/Project.csproj	✅Succeeded
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/httpwebrequest_begingetresponse.cs	✅Succeeded
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/Project.csproj	✅Succeeded
snippets/csharp/System.Net/WebRequest/BeginGetResponse/Project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/WebRequest/BeginGetResponse/webrequest_begingetresponse.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/HttpWebRequest_BeginGetResponse/VB/httpwebrequest_begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/VB/begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
xml/System.Net/HttpWebRequest.xml	✅Succeeded	View
xml/System.Net/WebRequest.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[learn-build-service-prod]

Learn Build status updates of commit ea80921:

✅ Validation status: passed

File	Status	Preview URL	Details
snippets/cpp/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/CPP/begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/cpp/VS_Snippets_Remoting/WebRequest_BeginGetResponse/CPP/webrequest_begingetresponse.cpp	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/HttpWebRequest/Abort/begingetresponse.cs	✅Succeeded	View
snippets/csharp/System.Net/HttpWebRequest/Abort/Project.csproj	✅Succeeded
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/httpwebrequest_begingetresponse.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/HttpWebRequest/EndGetResponse/Project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/WebRequest/BeginGetResponse/Project.csproj	✅Succeeded	n/a (file deleted or renamed)
snippets/csharp/System.Net/WebRequest/BeginGetResponse/webrequest_begingetresponse.cs	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/HttpWebRequest_BeginGetResponse/VB/httpwebrequest_begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
snippets/visualbasic/VS_Snippets_Remoting/System.Net.HttpWebRequest.BeginGetResponse/VB/begingetresponse.vb	✅Succeeded	n/a (file deleted or renamed)
xml/System.Net/HttpWebRequest.xml	✅Succeeded	View
xml/System.Net/WebRequest.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[gewarren]

Thank you!