[jdk11u-dev] RFR: 8339803: Acknowledge case insensitive unambiguous keywords in tzdata files

[Antonio Vieiro]

Backport of [JDK-8339803](https://bugs.openjdk.org/browse/JDK-8339803) from 17u. Related to tz-2024b timezone update.

Clean backport. Passed tier1 tests.

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Commit messages:
 - Backport 0d7b2729e4f4c0fec2dcfea65a0834732a408ee4

Changes: https://git.openjdk.org/jdk11u-dev/pull/2964/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2964&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339803
  Stats: 20 lines in 3 files changed: 4 ins; 0 del; 16 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2964.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2964/head:pull/2964

PR: https://git.openjdk.org/jdk11u-dev/pull/2964