Fixes JENKINS-45294, JENKINS-47425, JENKINS-47901, JENKINS-47942 + about 50 reported FindBugs issues (JENKINS-37566). There are 13 FindBugs issues left, work in progress.

* When -Dtest is set, set -DfailIfNoTests=false

* Rename profile to not imply only one test runs

There was a few typos in comments that have been addressed.
Also update the comment about the servlet fudge in plugin-pom

Add a comment about what <version>[x]</version> means as not everyone is
familiar with its syntax.

servlet-api is not a plugin :)