Fix regression plan trigger

It is not meant for build/PR gating time.

plans/regression.fmf

@@ -10,11 +10,10 @@ discover:
 
 # Adjust rules
 adjust+:
-  - because: "Plan to be ran when executed locally, or executed by CI system to gate a build or PR."
+  - because: "Plan to be ran when executed locally, or executed by CI system after updating an erratum."
     when: >-
       trigger is defined
-      and trigger != commit
-      and trigger != build
+      and trigger != update
     enabled: false
 
   - because: "On CentOS Stream 9, CRB repository must be enabled for various BuildRequires"