Enable cocoon test (#347)

flutter/flutter#138521 (reland PR: flutter/flutter#144273) is merged. Re-enable cocoon.

Author: QuncCccccc

registry/flutter_cocoon.test.disabled renamed to registry/flutter_cocoon.test

@@ -1,6 +1,6 @@
 [email protected]
 fetch=git clone https://github.com/flutter/cocoon.git tests
-fetch=git -C tests checkout 49af3c041c302c2abf76825b1e53ef3a2c5d1509
+fetch=git -C tests checkout 8880a7a15c3723a7e93caf7bd96650c93568b1e7
 update=dashboard
 # Runs flutter analyze, flutter test, and builds web platform
 test.posix=./test_utilities/bin/flutter_test_runner.sh dashboard