schemachanger: remove TODOTestTenantDisabled from SingleNodeTestClusterFactory.Run.

[shubhamdhama]

Tests count (est.): 1

We should remove TODOTestTenantDisabled to enable tenant testing for the datadriven and standard unit tests:

cockroach/pkg/sql/schemachanger/sctest/test_server_factory.go

Lines 74 to 86 in 67f3868

	func (f SingleNodeTestClusterFactory) Run(
	ctx context.Context, t *testing.T, fn func(_ serverutils.TestServerInterface, _ *gosql.DB),
	) {
	args := base.TestServerArgs{
	Knobs: base.TestingKnobs{
	JobsTestingKnobs: newJobsKnobs(),
	SQLExecutor: &sql.ExecutorTestingKnobs{
	UseTransactionalDescIDGenerator: true,
	},
	},
	// TODO(postamar): remove this
	DefaultTestTenant: base.TODOTestTenantDisabled,
	}

pkg/sql/schemachanger/sctest/backup.go
  235, 40: WithSchemaChangerKnobs(knobs).Run(ctx, t, runfn)
  335, 40: WithSchemaChangerKnobs(knobs).Run(ctx, t, runfn)

pkg/sql/schemachanger/sctest/cumulative.go
  103, 41: WithSchemaChangerKnobs(knobs).Run(ctx, t, runfn)
  252, 41: WithSchemaChangerKnobs(knobs).Run(ctx, t, runfn)
  296, 6: 		}).Run(ctx, t, func(s serverutils.TestServerInterface, db *gosql.DB) {
  386, 40: WithSchemaChangerKnobs(knobs).Run(ctx, t, runfn)

pkg/sql/schemachanger/sctest/decomp.go
  43, 11: 		factory.Run(ctx, t, func(_ serverutils.TestServerInterface, db *gosql.DB) {

pkg/sql/schemachanger/sctest/end_to_end.go
  66, 10: 	factory.Run(ctx, t, func(s serverutils.TestServerInterface, db *gosql.DB) {

pkg/sql/schemachanger/sctest/framework.go
  819, 5: 	}).Run(context.Background(), t, func(_ serverutils.TestServerInterface, db *gosql.DB) {
  925, 10: 	factory.Run(ctx, t, func(s serverutils.TestServerInterface, db *gosql.DB) {

pkg/sql/schemachanger/sctest/test_server_factory.go
  74, 39: SingleNodeTestClusterFactory) Run(

Informs: #138912
Epic: CRDB-48357

Jira issue: CRDB-48534