RFR: 8341028: Do not use lambdas or method refs for verifyConstantPool

[David M. Lloyd]

Currently, `ParserVerifier#verifyConstantPool` uses a `switch` to produce a `Runnable`, which is consumed by a `Consumer<Runnable>` (instantiated within a loop) which runs the task inside if a `try`/`catch`. We can eliminate a number of lambdas and method references, plus some allocation pressure, in this code by simplifying it so that the `switch` is itself run directly within the `try`/`catch`.

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Commit messages:
 - 8341028: Do not use lambdas or method refs for verifyConstantPool

Changes: https://git.openjdk.org/jdk/pull/21209/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21209&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341028
  Stats: 70 lines in 1 file changed: 29 ins; 33 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/21209.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21209/head:pull/21209

PR: https://git.openjdk.org/jdk/pull/21209