C++: Remove unneeded CPython toString overrides
C++: Remove unneeded CPython toString overrides

These were made redundant when a1e44041e changed their parent class to
extend `Element`.

github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql,github/codeql