Replace jq with Actions expression for proxy_urls validation

For the sake of consistency with the other pre-existing validation code.

Author: mario-campos

pr-checks/checks/start-proxy.yml

@@ -39,13 +39,8 @@ steps:
     run: exit 1
 
   - name: Validate proxy_urls contains expected registries
-    env:
-      PROXY_URLS: ${{ steps.proxy.outputs.proxy_urls }}
-    run: |
-      jq --null-input --exit-status '
-        env.PROXY_URLS
-        | fromjson
-        | length == 2 and
-          any(.[]; .type=="maven-repository" and .url=="https://acme.jfrog.io/artifactory/my-maven-registry") and
-          any(.[]; .type=="maven-repository" and .url=="https://repo1.maven.org/maven2")
-      '
+    if: |
+      join(fromJSON(steps.proxy.outputs.proxy_urls)[*].type, ',') != 'maven-repository,maven-repository'
+      || !contains(fromJSON(steps.proxy.outputs.proxy_urls)[*].url, 'https://acme.jfrog.io/artifactory/my-maven-registry')
+      || !contains(fromJSON(steps.proxy.outputs.proxy_urls)[*].url, 'https://repo1.maven.org/maven2')
+    run: exit 1