Enable Cert based auth in daily and PR pipelines (#2098)

The secret key for lab vault has been replaced with the certificate.

Pipeline run :
https://identitydivision.visualstudio.com/Engineering/_build/results?buildId=1297001&view=results

Author: somalaya

azure-pipelines/pull-request-validation/pr-msal.yml

@@ -45,6 +45,7 @@ jobs:
     clean: true
     submodules: recursive
     persistCredentials: True
+  - template: azure-pipelines/templates/steps/automation-cert.yml@common
   - task: JavaToolInstaller@0
     displayName: Use Java 11
     inputs:
@@ -66,7 +67,7 @@ jobs:
   - task: Gradle@2
     displayName: Run Unit tests
     inputs:
-      tasks: msal:testLocalDebugUnitTest -Plabtest -PlabSecret=$(LabVaultAppSecret) -ProbolectricSdkVersion=${{variables.robolectricSdkVersion}}
+      tasks: msal:testLocalDebugUnitTest -Plabtest -PlabSecret=$(LabVaultAppCert) -ProbolectricSdkVersion=${{variables.robolectricSdkVersion}}
       javaHomeSelection: $(BuildParameters.javaHomeSelection)
       jdkVersion: 1.11
 - job: spotbugs