Update tests to use raw strings

[CyrusNajmabadi]

No description provided.

[DoctorKrolic]

Can you please revert UseDeconstructionTest changes, so we can merge #67052 to improve it instead?

[sharwell]

❓ Why is a mechanical factoring PR containing code changes? this should have preserved the spacing.

[CyrusNajmabadi]

it's the mechanical approach that removes starting/ending lines, and remove indentation. THat way we don't have tests that look like this:

var test = """

class C 
                        {
                               void Foo()
                               {
                               }
                        }
                   }

"""

But instead get the much more clearly desired:

var test = """
           class C 
           {
               void Foo()
               {
               }
           }
           """;

[sharwell]

❓ Why is a mechanical factoring PR containing code changes? This should not have changed.

[CyrusNajmabadi]

so changing the test here just changed diagnostic spans. That's pointless pain (since this test is not seeking to verify that you get a "Program using top-level statements must be an executable." error). So this was changed to remove the error, and just pass teh flag to teh compiler that ensures we test the thing we care about, without extraneous (position-sensitive) data in it.