test: mark test-runner-watch-mode as flaky

Author: joyeecheung

test/parallel/parallel.status

@@ -23,6 +23,8 @@ test-child-process-stdio-reuse-readable-stdio: PASS, FLAKY
 test-domain-error-types: PASS,FLAKY
 # https://github.com/nodejs/node/issues/47420
 test-file-write-stream4: PASS,FLAKY
+# https://github.com/nodejs/node/issues/49605
+test-runner-watch-mode: PASS,FLAKY
 
 [$system==macos]
 # https://github.com/nodejs/node/issues/42741