RFR: 8349176: Speed up Integer/Long.toString via StringConcatHelper::newArray [v3]

[Shaojin Wen]

> The byte[] allocated in Integer/Long.toString is fully filled, so we can use StringConcatHelper::newArray to create byte[] to improve performance.

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge remote-tracking branch 'upstream/master' into allocate_un_init_202501
   
   # Conflicts:
   #	src/java.base/share/classes/java/lang/Integer.java
   #	src/java.base/share/classes/java/lang/Long.java
 - use StringConcatHelper.newArray
 - simplify
 - use Unsafe.allocateUninitializedArray
 - revert StringConcatHelper newArray change
 - copyright
 - remove duplicate check
 - allocateUninitializedArray

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Changes: https://git.openjdk.org/jdk/pull/23353/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23353&range=02
  Stats: 6 lines in 2 files changed: 2 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/23353.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23353/head:pull/23353

PR: https://git.openjdk.org/jdk/pull/23353