[jdk17u-dev] RFR: 8334490: Normalize string with locale invariant `toLowerCase()`

[Goetz Lindenmaier]

I backport this for parity with 17.0.15-oracle.

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Commit messages:
 - Backport 265a0f5547d0ddb220391aef679c122768f02a00

Changes: https://git.openjdk.org/jdk17u-dev/pull/3093/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3093&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334490
  Stats: 7 lines in 1 file changed: 1 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3093.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3093/head:pull/3093

PR: https://git.openjdk.org/jdk17u-dev/pull/3093