Review & clean up GlobalSuppression.cs

[CleanCodeDeveloper]

Review & clean up GlobalSuppression.cs. Create dedicated issues for warnings which should be unsuppressed.

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for stuff supressed, lets create dedicated issues to unsupress

Originally posted by @crutkas in #16543 (comment)

[CleanCodeDeveloper]

Can be assigned to me :)

[htcfreek]

Yes. This is indeed a must do item. I have added a suppression for the suppression list in #16662.