Use 4 core runners

Author: sutaakar

.github/workflows/e2e_tests.yaml

@@ -27,7 +27,7 @@ concurrency:
 jobs:
   kubernetes-e2e:
 
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-20.04-4core
 
     steps:
       - name: Cleanup

.github/workflows/olm_tests.yaml

@@ -19,7 +19,7 @@ concurrency:
 
 jobs:
   kubernetes-olm-upgrade:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-20.04-4core
     timeout-minutes: 60
     env:
       OLM_VERSION: v0.24.0