CI: Run the main workflow on a self-hosted runner

We started experiencing timeouts on the default GitHub runners due to
the lengthy setup time for the Yocto build environment. This change
modifies the main CI workflow to utilize a self-hosted runner that
has less computing limitations.

Author: deribaucourt

.github/workflows/main.yml

@@ -10,11 +10,14 @@ on:
   pull_request:
     branches:
       - '*'
+  schedule: # This run is just to keep the self-hosted runner active. They get deleted after 14 days of inactivity.
+    - cron: '0 8 * * 1'  # Run weekly on Mondays at 9AM CET (8AM UTC)
 
 jobs:
   build-test-vscode:
 
-    runs-on: ubuntu-latest
+    # We need a faster runner with a Yocto cache in order for the tests to complete in time
+    runs-on: self-hosted
 
     defaults:
       run: