RFR: 8306597: Improve string formatting in EquivMapsGenerator.java [v4]

[Justin Lu]

> Please review changes to `EquivMapsGenerator.java` (which is used to generate the Locale equivalencies for the JDK).
> 
> The file previously used large concatenated Strings, which are now replaced with text blocks, in addition to some cleanup. No functionality is changed, the Locale equivalencies builds the same.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Review: capitalize and move footer text. Add comments to main

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13935/files
  - new: https://git.openjdk.org/jdk/pull/13935/files/33fd7993..b4e6e683

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13935&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13935&range=02-03

  Stats: 13 lines in 1 file changed: 10 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13935.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13935/head:pull/13935

PR: https://git.openjdk.org/jdk/pull/13935