NMS-6823 - fix the TopReportPluginTest

Also refactored the report plugin tests a bit to not pull in ALL
of the freakin' DAO test infrastructure just to test a simple
plugin.
Merge remote-tracking branch 'origin/1.12'

Conflicts:
	features/system-report/pom.xml
	features/system-report/src/main/java/org/opennms/systemreport/AbstractSystemReportPlugin.java
	features/system-report/src/main/java/org/opennms/systemreport/system/ThreadReportPlugin.java
	features/system-report/src/main/java/org/opennms/systemreport/system/TopReportPlugin.java
	features/system-report/src/test/java/org/opennms/systemreport/system/SystemReportPluginTest.java
	features/system-report/src/test/java/org/opennms/systemreport/system/TopReportPluginTest.java
NMS-6825 wait for full DNS server startup

Fix a potential race condition by waiting for DNS threads to fully
come up before start() returns.
NMS-6824 fixes for testGetAvailability

I modified the remote poller test to use a single set
of start/end times rather than re-instantiating Date
or calling currentTimeMillis multiple times, to create
less jitter while doing time-related math.
NMS-6828 giving up on VacuumdTest

It would take WAY too much work to rearchitect Vacuumd to be
properly testable.  We've gone so far into code debt that after
a vote, we've decided to declare code bankruptcy.
Merge remote-tracking branch 'origin/1.12'

Conflicts:
	opennms-alarms/daemon/src/test/java/org/opennms/netmgt/vacuumd/VacuumdTest.java
Merge remote-tracking branch 'origin/master' into pjsm/2.0