=test harden test_gossip_shouldEventuallyStopSpreading

[ktoso]

Motivation:

Failure from nightly CI.

The test is too aggressive, it is probabilistic how many exact rounds will happen and it depends on ordering and timing of message exchanges.

All this test wants to check is that messages eventually stop flowing, we can check this with a more frequent gossip round and just checking that they definitely stop, rather than checking the exact number on "happy path"

Modifications:

Loosen up the checks but still check what the test is intended to be testing

Result:

• Resolves a flaky test

[ktoso]

• 5.3 green, except the known compilation release error...
• 5.2 weird timeout :-/

13:07:05 Test Suite 'RemoteActorRefProviderTests' started at 2020-09-25 04:07:05.551
13:07:05 Test Case 'RemoteActorRefProviderTests.test_remoteActorRefProvider_shouldMakeRemoteRef_givenSomeRemotePath' started at 2020-09-25 04:07:05.551
13:07:05 [4:7:05.5560] /code/Tests/DistributedActorsTests/Cluster/RemoteActorRefProviderTests.swift:52 : Made remote ref: ActorRef<String>(sact://[email protected]:2322/user/henry/hacker)
13:07:05 Test Case 'RemoteActorRefProviderTests.test_remoteActorRefProvider_shouldMakeRemoteRef_givenSomeRemotePath' passed (0.011 seconds)
13:07:05 Test Case 'RemoteActorRefProviderTests.test_remoteActorRefProvider_shouldResolveDeadRef_forSerializedDeadLettersRef' started at 2020-09-25 04:07:05.561
13:07:05 [4:7:05.5670] /code/Tests/DistributedActorsTests/Cluster/RemoteActorRefProviderTests.swift:119 : Made remote ref: ActorRef<String>(/dead/letters)
13:07:05 Test Case 'RemoteActorRefProviderTests.test_remoteActorRefProvider_shouldResolveDeadRef_forSerializedDeadLettersRef' passed (0.01 seconds)
13:07:05 Test Case 'RemoteActorRefProviderTests.test_remoteActorRefProvider_shouldResolveDeadRef_forTypeMismatchOfActorAndResolveContext' started at 2020-09-25 04:07:05.572
13:22:05 Build timed out (after 15 minutes). Marking the build as failed.
13:22:05 $ ssh-agent -k
13:22:05 unset SSH_AUTH_SOCK;

This test is not doing anything that could take long time...

[ktoso]

@swift-server-bot test this please