RFR: 8375066: Test tools/sincechecker/modules/java.base/JavaBaseCheckSince.java broken by JDK-8369564

[Liam Miller-Cushon]

Please consider this fix for JDK-8375066, which adds missing `@since 27` tags to methods added in [JDK-8375066](https://bugs.openjdk.org/browse/JDK-8369564).

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Commit messages:
 - 8375066: Test tools/sincechecker/modules/java.base/JavaBaseCheckSince.java broken by JDK-8369564

Changes: https://git.openjdk.org/jdk/pull/29179/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29179&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375066
  Stats: 3 lines in 2 files changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29179.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29179/head:pull/29179

PR: https://git.openjdk.org/jdk/pull/29179