MiNiFi IT Improvements

1. We should add

mvn -pl minifi/minifi-c2/minifi-c2-assembly -am install -T1C -DskipTests -P targz
mvn -pl minifi/minifi-c2/minifi-c2-docker -am install -T1C -DskipTests -P docker

to nifi/minifi/minifi-integration-tests/README.md to make it self contained, as minifi-integration-tests require minifi-c2-docker image.

2. StandaloneYamlTest.verifyLogEntries test seems to be unstable as sometimes the particular container is started too slowly, and in the verifyLogEntries method the while loop exits before all the required log entries are found.

Possible solutions:

• quick and dirty: insert a Thread.sleep before verifyLogEntries, so the docker container will have time to start
• proper: refactor the verifyLogEntries method, to not check on null, but poll until the test criteria is met or a timeout is reached