RFR: 8338936: StringConcatFactory optimize the construction of MethodType and MethodTypeDesc [v2]

[Shaojin Wen]

> optimize the construction of MethodType and MethodTypeDesc to reduce memory allocate

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  use MethodTypeDescImpl.ofValidated

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20704/files
  - new: https://git.openjdk.org/jdk/pull/20704/files/d8b60139..727ec217

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20704&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20704&range=00-01

  Stats: 27 lines in 1 file changed: 1 ins; 0 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/20704.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20704/head:pull/20704

PR: https://git.openjdk.org/jdk/pull/20704