Use ubuntu-latest-16-cores from CNCF for e2e

Signed-off-by: Sascha Schwarze <schwarzs@de.ibm.com>

Author: SaschaSchwarze0

.github/workflows/ci.yml

@@ -151,7 +151,7 @@ jobs:
           # newest LTS that exists at the time of our planned next release
           - v0.65.5 # RETAIN-COMMENT: TEKTON_NEWEST_LTS
       max-parallel: 4
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-latest-16-cores
     steps:
       - name: Maximize build space
         uses: easimon/maximize-build-space@fc881a613ad2a34aca9c9624518214ebc21dfc0c