RFR: 7065228: To interpret case-insensitive string locale independently

[Naoto Sato]

On Tue, 16 May 2023 10:38:52 GMT, Darragh Clarke <duke at openjdk.org> wrote:

> Updated instances of `toLowerCase` and `toUpperCase` in several net and io files to specify `Locale.ROOT` to ensure that case conversion issues don't occur,
> 
> I didn't add any new tests but ran tier 1-3 with no issues

LGTM. Nice clean-up!

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Marked as reviewed by naoto (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14006#pullrequestreview-1428917297