RFR [11]: Bulk backports to sh/jdk11

[Aleksey Shipilev]

That repository is under stabilization for release, so we would like to push only the important
fixes that improve reliability, UX and testing:
 [backport] 8224881: Shenandoah: trashing "Collection Set, Pinned" region during Degenerated GC
 [backport] 8225046: Shenandoah metrics logs refactoring
 [backport] 8225017: [TESTBUG] gc/shenandoah/oom/TestThreadFailure.java takes too long

Full webrev:
  http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20190614/webrev.01/

Testing: hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey