t/perf: avoid copying builtin fsmonitor files into test repo

t/perf: avoid copying builtin fsmonitor files into test repo

Do not copy any of the various fsmonitor--daemon files from the .git
directory of the (GIT_PREF_REPO or GIT_PERF_LARGE_REPO) source repo
into the test's trash directory.

When perf tests start, they copy the contents of the source repo into
the test's trash directory.  If fsmonitor is running in the source repo,
there may be control files, such as the IPC socket and/or fsmonitor
cookie files.  These should not be copied into the test repo.

Unix domain sockets cannot be copied in the manner used by the test
setup, so if present, the test setup fails.

Cookie files are harmless, but we should avoid them.

The builtin fsmonitor keeps all such control files/sockets in
.git/fsmonitor--daemon*, so it is simple to exclude them.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>