RFR: 8368345: Remove leftover includes of strongRootsScope.hpp

[Francesco Andreuzzi]

#27336 and #27385 replaced some `StrongRootsScope` usages with `ThreadsClaimTokenScope`. Some includes to `strongRootsScope.hpp` can now be removed.

Passes tier1.

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Commit messages:
 - rm

Changes: https://git.openjdk.org/jdk/pull/27442/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27442&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368345
  Stats: 2 lines in 2 files changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27442.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27442/head:pull/27442

PR: https://git.openjdk.org/jdk/pull/27442