RFR: 8367796: Rename AtomicAccess gtests

[Kim Barrett]

Please review this trivial renaming change. AtomicAccess gtest names and
supporting classes are being renamed to use "AtomicAccess" nomenclature,
rather than just "Atomic". (The potential for ODR violations could have been
eliminated by instead using anonymous namespaces, but use of those is still
not permitted in HotSpot.)

Testing: mach5 tier1

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Commit messages:
 - rename AtomicAccess gtests

Changes: https://git.openjdk.org/jdk/pull/27330/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27330&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367796
  Stats: 52 lines in 1 file changed: 1 ins; 0 del; 51 mod
  Patch: https://git.openjdk.org/jdk/pull/27330.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27330/head:pull/27330

PR: https://git.openjdk.org/jdk/pull/27330