optional_spec111_maySupportMultiSubscribe has no delay before checking async errors

[ktoso]

Discovered during updating Akka Streams, the used verify method does not perform a delay, so this test can leak the async errors to the following.

Fix is to replace:

// NOT: env.verifyNoAsyncErrors();
env.verifyNoAsyncErrors(env.defaultTimeoutMillis());

I suspect other places have this as well... We talked about these at some point and added them at the end of each test. Must have slipped if it currently performs the delay or not. I'll go over all tests to verify the proper verifyNoAsyncErrors is used.

Reported by @patriknw, thanks!