[11] RFR: Clean up leftover differences against upstream

[Aleksey Shipilev]

https://cr.openjdk.java.net/~shade/shenandoah/11u-cleanup-1/webrev.01/

Scrubbed the 11u webrev [1], these are the non-essential differences against 11u upstream.

Testing: Linux {x86_64, aarch64} x {fastdebug, release}, hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey

[1] https://builds.shipilev.net/patch-openjdk-shenandoah-jdk11/