RFR: 8253222: Shenandoah: unused AlwaysTrueClosure after JDK-8246591

[Aleksey Shipilev]

Static analysis shows the AlwaysTrueClosure is not needed in `ShenandoahRootScanner::roots_do` after JDK-8246591.

Testing: Linux x86_64 tier1_gc_shenandoah

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Commit messages:
 - 8253222: Shenandoah: unused AlwaysTrueClosure after JDK-8246591

Changes: https://git.openjdk.java.net/jdk/pull/201/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=201&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253222
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/201.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/201/head:pull/201

PR: https://git.openjdk.java.net/jdk/pull/201