RFR: 8357185: Redundant local variables with unconditionally matching primitive patterns

[Chen Liang]

A commit in the implementation of JEP 455, https://github.com/openjdk/jdk/pull/15638/commits/ceee1e4c08457a0793fdfb556db99e057a947af1, added redundant synthetic local variable for trivial `instanceof int`-ish type conversion operations in the javac AST. Such conversions have been present since the introduction of record patterns, and previously they consistently lower to the part before `instanceof`. With this change, the introduced redundant variable is visible in the class file, as seen in the JBS issue.

Testing: langtools/tools/javac

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Commit messages:
 - Fix
 - Fixup
 - 8357185: Redundant local variables with unconditionally matching primitive patterns

Changes: https://git.openjdk.org/jdk/pull/26107/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26107&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357185
  Stats: 96 lines in 2 files changed: 96 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26107.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26107/head:pull/26107

PR: https://git.openjdk.org/jdk/pull/26107