[8u] Pick up 8u282 GA to sh/jdk8

[Aleksey Shipilev]

I would like to pick up the 8u282 GA to sh/jdk8.

Hotspot requires resolving the following conflict:

aarch64-port/jdk8u-shenandoah has:
   Shenandoah: Fix racy update of code roots
   https://hg.openjdk.java.net/aarch64-port/jdk8u-shenandoah/hotspot/rev/76dace090781

sh/jdk8 has:
   [backport] 8229474: Shenandoah: Cleanup CM::update_roots()
   https://hg.openjdk.java.net/shenandoah/jdk8/hotspot/rev/03dc7e990da2

As far as I can tell, sh/jdk8 removes _update_code_cache, and so aarch64-port/jdk8u-shenandoah 
change is no longer relevant. Therefore, I accepted the sh/jdk8 side in that conflict.

Every other repo is pulled without merges.

Testing: hotspot_gc_shenandoah {fastdebug, release}

-- 
Thanks,
-Aleksey