[jdk21u-dev] RFR: 8316696: Remove the testing base classes: IntlTest and CollatorTest

[Goetz Lindenmaier]

I backport this for parity with 21.0.4-oracle.

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Commit messages:
 - Backport b859da9c548fbd1463b336059d1c55312c7b7ba4

Changes: https://git.openjdk.org/jdk21u-dev/pull/372/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=372&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316696
  Stats: 4465 lines in 79 files changed: 922 ins; 1081 del; 2462 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/372.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/372/head:pull/372

PR: https://git.openjdk.org/jdk21u-dev/pull/372