GitalyClient.get_request_count is disabled on known N + 1's

Since the first RC of %11.10 GitLab-Rails logs the number of Gitaly request made, which is very useful for finding the worst offenders of N + 1's on GitLab.com. But if such a Gitaly call gets ignored as it's called in a allow_n_plus_1, it's not recorded, hiding the true number of Gitaly RPC's called.

/cc @stanhu