ci: don't use latest runner

- For now, run the e2e tests on Ubuntu 22.04 because the tests are failing due to not using the bwrap apparmor profile:

pressure-vessel-wrap[2993]: E: Child process exited with code 1: bwrap: setting up uid map: Permission denied

Fix this later in a separate commit or pull request

.github/workflows/e2e.yml

@@ -11,7 +11,7 @@ permissions:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4