C++: Remove FPs from cpp/too-few-arguments

[calumgrant]

Fixes https://github.com/github/codeql-c-team/issues/2462

Pull Request checklist

All query authors

• A change note is added if necessary. See the documentation in this repository.
• All new queries have appropriate .qhelp. See the documentation in this repository.
• QL tests are added if necessary. See Testing custom queries in the GitHub documentation.
• New and changed queries have correct query metadata. See the documentation in this repository.

Internal query authors only

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