[Maven] Fix flaky test-plugins

Logging in maven has been slightly changed, so it no longer matches the old patterns. It was flaky because sometimes it loaded the plexus artifact (and sometimes it didn't) and such event was shown in the log with different log message

libraries/tools/kotlin-maven-plugin-test/src/it/test-plugins/verify.groovy

@@ -26,10 +26,10 @@ State state = buildLogFile.readLines().collect { it.replaceAll("\\u001b[^m]*m",
     def m = pattern.matcher(line)
     if (m.find()) {
         acc.currentPlugin = m.group(1)
-    } else if (line.startsWith("[INFO] Downloaded:") ||
-               line.startsWith("[INFO] Downloading:") ||
-               line.startsWith("Downloaded:") ||
-               line.startsWith("Downloading:") ||
+    } else if (line.startsWith("[INFO] Downloaded") ||
+               line.startsWith("[INFO] Downloading") ||
+               line.startsWith("Downloaded") ||
+               line.startsWith("Downloading") ||
                line.startsWith("[INFO] PERF:")) {
         // ignore line
     } else if (acc.currentPlugin == "kotlin-maven-plugin") {