Fix PoliCheck InvalidArgumentsError (remove missing exclusion file path); fix CredScan suppression format

Author: RyAuld

.Pipelines/credscan-exclusion.json

@@ -2,15 +2,12 @@
   "tool": "Credential Scanner",
   "suppressions": [
     {
-      "placeholder": "placeholder",
-      "_justification": "tests/certificate-with-password.pfx is a test fixture certificate used only in unit tests. It is not a production credential.",
-      "file": "tests/certificate-with-password.pfx"
+      "file": "certificate-with-password.pfx",
+      "_justification": "Self-signed certificate used only in unit tests. Not a production credential."
     },
     {
-      "placeholder": "placeholder",
-      "_justification": "tests/test_mi.py line 385 contains a WWW-Authenticate challenge header value used as a test fixture in a mock HTTP response. It is not a real credential.",
-      "file": "tests/test_mi.py",
-      "line": "385"
+      "file": "test_mi.py",
+      "_justification": "WWW-Authenticate challenge header value used as a mock HTTP response fixture in unit tests. Not a real credential."
     }
   ]
 }

.Pipelines/template-pipeline-stages.yml

@@ -57,7 +57,6 @@ stages:
       displayName: 'Run PoliCheck'
       inputs:
         targetType: F
-        optionsUEPATH: '$(Build.SourcesDirectory)/build/policheck_exclusion.xml'
       continueOnError: true
 
     - task: securedevelopmentteam.vss-secure-development-tools.build-task-credscan.CredScan@3