[clang-tidy] Ensure functions are anchored in the global namespace (for cert-err-33) (#99380)

Summary:
The regular expressions match functions that aren't anchored in the
global namespace. For example `::remove` matches any object with a
`removeXyz` method. This change is to remove these false positives

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Differential Revision: https://phabricator.intern.facebook.com/D60251178

Author: matthew-f