RFR: 8344361: Restore null return for invalid services from legacy providers

[Sean Coffey]

Correct a corner case where null should be returned if a service from the legacyMap is marked invalid. 

New test case added.

-------------

Commit messages:
 - rename test
 - 8344361

Changes: https://git.openjdk.org/jdk/pull/23201/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23201&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344361
  Stats: 50 lines in 2 files changed: 50 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/23201.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23201/head:pull/23201

PR: https://git.openjdk.org/jdk/pull/23201