RFR: 8269803: G1: remove unnecessary NoRefDiscovery

Fri Jul 2 11:06:18 UTC 2021

Simple change of removing the unnecessary disable of ref-discovery for CM during young-gc pause.

Test: hotspot_gc

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Commit messages:
 - cm_discovery

Changes: https://git.openjdk.java.net/jdk/pull/4664/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4664&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269803
  Stats: 27 lines in 2 files changed: 0 ins; 27 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4664.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4664/head:pull/4664

PR: https://git.openjdk.java.net/jdk/pull/4664