gitlab-ci: Cope with OBS slowdown

OBS 2.10 has just been deployed and we started hitting timeouts. Being more patient, does not seem to help.

In the meantime, skip OBS scanning by default unless the SKIP_OBS var is set to no.

Task: https://phabricator.apertis.org/T8880

bin/packaging-check-invariants

@@ -560,7 +560,7 @@ class Error(Exception):
 
 
 def hack_skip_obs():
-    return os.environ.get("SKIP_OBS") != "yes"
+    return os.environ.get("SKIP_OBS") == "yes"
 
 
 def is_stable_channel(channel):