[EngSys] add condition for publishing test proxy log (Azure#29610)

The other test proxy steps have this condition. This PR adds the same to
publish step as well.

Author: jeremymeng

eng/pipelines/templates/steps/test.yml

@@ -91,8 +91,9 @@ steps:
     condition: and(always(),eq(variables['TestType'], 'browser'))
     displayName: "Publish browser unit test results"
 
-  - template: /eng/common/pipelines/templates/steps/publish-1es-artifact.yml
-    parameters:
-      ArtifactPath: '$(Build.ArtifactStagingDirectory)/test-proxy.log'
-      ArtifactName: 'test proxy logs $(Agent.JobName)'
-      SbomEnabled: false
+  - ${{ if eq(parameters.TestProxy, true) }}:
+    - template: /eng/common/pipelines/templates/steps/publish-1es-artifact.yml
+      parameters:
+        ArtifactPath: '$(Build.ArtifactStagingDirectory)/test-proxy.log'
+        ArtifactName: 'test proxy logs $(Agent.JobName)'
+        SbomEnabled: false