github: eliminate duplicate CI runs for branch pushes

This prevents wasteful duplicate CI execution that occurred when pushing
to a branch and creating a PR from it. Now only main branch pushes and
PRs to main trigger CI, with ci-testing/* branches available for testing
workflow changes before submission.

Generated-by: Claude AI
Signed-off-by: Daniel Gomez <[email protected]>

Author: dkruces

.github/workflows/kdevops.yml

@@ -7,10 +7,11 @@ on:
     - cron: '0 14 * * *'  # Daily at 2 PM UTC
   push:
     branches:
-      - '**'
+      - main
+      - 'ci-testing/**'
   pull_request:
     branches:
-      - '**'
+      - main
   workflow_dispatch:
     inputs:
       ci_workflow: