Need to add close button to the "important !.." warning in expression editor

[RDPerera]

Description

Need to add a close button to the

'Important!
Payload suggestions are generated based on the first request payload defined in the 'Start' node. If no payloads are defined yet, please add one in the 'Start' node of the diagram.

warning in the expression editor, Since it's not going even after we added a start-payload and disturbing to the user while editing the expressions.

Steps to Reproduce

1. Add a sample payload to the start
2. Open Variable mediator
3. Edit the payload from the expression editor

Version

1.9.25021613

Environment Details (with versions)

No response

[SanojPunchihewa]

Related issue #811