Specify Quick mode for sonobuoy test (#9499)

The certified-conformance mode took 2+ hours and that was too long
by comparing Quick mode which was specified previously.
So this updates the mode to Quick again.

tests/testcases/100_check-k8s-conformance.yml

@@ -5,7 +5,7 @@
     sonobuoy_arch: amd64
     sonobuoy_parallel: 30
     sonobuoy_path: /usr/local/bin/sonobuoy
-    sonobuoy_mode: certified-conformance
+    sonobuoy_mode: Quick
 
   tasks:
   - name: Run sonobuoy