RFR: 8260005: Shenandoah: Remove unused AlwaysTrueClosure in ShenandoahConcurrentRootScanner::roots_do()

[Zhengyu Gu]

Please review this trivial cleanup that removes unused AlwaysTrueClosure in ShenandoahConcurrentRootScanner::roots_do()

Test:
- [x] hotspot_gc_shenandoah

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Commit messages:
 - Init update

Changes: https://git.openjdk.java.net/jdk/pull/2152/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2152&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260005
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2152.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2152/head:pull/2152

PR: https://git.openjdk.java.net/jdk/pull/2152