<i18n dev> RFR: 8287187: Utilize HashMap.newHashMap() in CLDRConverter

[Naoto Sato]

Refactoring the leftover self-calculations of the optimized `HashMap` initial value with `newHashMap()` method. Also replaced some string literals using text blocks for better readability. Confirmed that the output resource bundle sources are effectively (sans indentation) the same as the original ones.

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Commit messages:
 - 8287187: Utilize HashMap.newHashMap() in CLDRConverter

Changes: https://git.openjdk.java.net/jdk/pull/8887/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8887&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287187
  Stats: 65 lines in 1 file changed: 8 ins; 1 del; 56 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8887.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8887/head:pull/8887

PR: https://git.openjdk.java.net/jdk/pull/8887