[Clang] Fix filtering of inline namespaces for friend functions

PR D135370 implemented a performance improvement but it restricted the filtering
of declaration from inline namespace too much. In particular it did not filter
for the function template case.

This led to a regression and this PR removes that check.

This fixes: https://github.com/llvm/llvm-project/issues/61851

Differential Revision: https://reviews.llvm.org/D147762