[jdk11u-dev] RFR: 8323515: Create test alias "all" for all test roots

[Aleksey Shipilev]

Improves JDK 17u testability by allowing to run all tests at once. There was a contextual conflict in langtools definitions, which misses most of the definitions added later with JDK-8267162. Also, libtest testgroup is defined only later with JDK-8211977. Test groups sanity is going to be tested with GHA.

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Commit messages:
 - Backport 8b9bf758801400e4491326cd4c90fc117b9d97e1

Changes: https://git.openjdk.org/jdk11u-dev/pull/2543/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2543&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323515
  Stats: 37 lines in 4 files changed: 34 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2543.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2543/head:pull/2543

PR: https://git.openjdk.org/jdk11u-dev/pull/2543