Refactoring to suppress CodeQL false positives

[Avery-Dunn]

#904 added suppressions for various CodeQL issues described in #899, however, after it was merged into main and scanned again two of the issues were still not suppressed.

This PR does some small refactoring to try to suppress the remaining false-positive flags:

• DefaultHttpClientManagedIdentity: the suppression comment was originally above the flagged variable, though the behavior that caused the flag was assigned to the variable elsewhere
  • This has been refactored so the problematic block of code all begins on the same line, which will hopefully be correctly picked up by the scanner
• Samples folder: there are two samples (meant for manual testing by devs) that use a class called CookieHelper and the same suppression comment was added to both lines of flagged code, however only one of the flags were suppressed
  • The suppression comment that did not work now has the ID of the CodeQL issue rather than the name, and the wording in the comment adjusted in case the scanner has some sort of issue with duplicate comments