GHA/windows: avoid libtool wrapper for test and server executables

GHA/windows: avoid libtool wrapper for test and server executables

This makes `runtests.pl` run the final executables directly.
Before this patch it called the autotools/libtool wrapper tool, which
then called the final executables.

This solution was already used for `curl.exe`.

Applies to tests run in the `mingw, AM x86_64 c-ares U` job, which still
shows unexplained flakiness.

Also makes tests finish 45 seconds faster.

Ref: #14854
Follow-up to 1a2d38c47c7825ad4d993d10664a45be3e3bbb58 #15437
Closes #15662