Use ubuntu-22.04 in the check-style step in CI (#23118)

.github/workflows/ci.yml

@@ -66,7 +66,7 @@ jobs:
         run: if [[ -n $(git status --porcelain) ]]; then echo "Please update the serialized files using 'make gen-serialized'"; exit 1; fi
   check-mattermost-vet:
     name: Check style
-    runs-on: ubuntu-latest-8-cores
+    runs-on: ubuntu-22.04
     defaults:
       run:
         working-directory: server