create_manpage_completions: ignore gcloud-* man pages

Google cloud CLI ships >10k man pages for subcommands, but the
completions are not useful because they don't know to replace
underscores by spaces, e.g. in:

	complete -c gcloud_access-approval_requests_approve

We also ship gcloud completions, so the generated ones should not
be used.

share/tools/create_manpage_completions.py

@@ -799,7 +799,9 @@ def parse_manpage_at_path(manpage_path, output_directory):
         "cargo-",
         "ffmpeg-",
         "flatpak-",
+        "gcloud_",
         "git-",
+        "jj-",
         "npm-",
         "openssl-",
         "ostree-",