Apply general test task timeout

build.gradle

@@ -1,3 +1,5 @@
+import java.time.Duration
+
 import static org.spockframework.gradle.AsciiDocLinkVerifier.verifyAnchorlessCrossDocumentLinks
 import static org.spockframework.gradle.AsciiDocLinkVerifier.verifyLinksAndAnchors
 
@@ -193,6 +195,8 @@ subprojects {
     //Required for building on Travis' container-based infrastructure to not be killed with
     //'exit code 137' - https://github.com/travis-ci/travis-ci/issues/5582
     jvmArgs '-Xmx512m'
+    // As a generous general timeout, instead of the 6h of GHA.
+    timeout = Duration.ofMinutes(15)
   }
 
   tasks.register("allDependencyInsight", DependencyInsightReportTask) {}