HSEARCH-5094 Don't even try to push to the remote cache in pull requests

The credentials are only available when building pull requests
on Jenkins, and those credentials don't give write access to the build
cache, so let's spare ourselves the warnings about 403 errors.

.mvn/gradle-enterprise.xml

@@ -32,7 +32,7 @@
         </local>
         <remote>
             <enabled>#{properties['no-build-cache'] == null}</enabled>
-            <storeEnabled>#{env['CI'] != null and env['GRADLE_ENTERPRISE_ACCESS_KEY'] != null and env['GRADLE_ENTERPRISE_ACCESS_KEY'] != ''}</storeEnabled>
+            <storeEnabled>#{env['CI'] != null and env['CHANGE_ID'] == null and env['GITHUB_BASE_REF'] == null and env['GRADLE_ENTERPRISE_ACCESS_KEY'] != null and env['GRADLE_ENTERPRISE_ACCESS_KEY'] != ''}</storeEnabled>
         </remote>
     </buildCache>
 </gradleEnterprise>