test: increase debugger waitFor timeout on macOS and Windows

The test-debugger-restart-message test is flaky on macOS CI because the
Debugger.getScriptSource CDP round-trip in the initial break handler
can be slow under CI load, causing the 15s timeout to be exceeded.

Increase the macOS/Windows timeout from 15s to 30s to provide adequate
headroom.

Author: mcollina

test/common/debugger.js

@@ -8,10 +8,12 @@ const BREAK_MESSAGE = new RegExp('(?:' + [
 ].join('|') + ') in', 'i');
 
 let TIMEOUT = common.platformTimeout(10000);
-// Some macOS and Windows machines require more time to receive the outputs from the client.
+// Some macOS and Windows machines require more time to receive the outputs from the
+// client, especially under CI load where the async Debugger.getScriptSource CDP
+// round-trip in the initial break handler can be slow.
 // https://github.com/nodejs/build/issues/3014
 if (common.isWindows || common.isMacOS) {
-  TIMEOUT = common.platformTimeout(15000);
+  TIMEOUT = common.platformTimeout(30000);
 }
 
 function isPreBreak(output) {