RFR: 8315880: change LockingMode default from LM_LEGACY to LM_LIGHTWEIGHT

[Roman Kennke]

On Mon, 18 Sep 2023 20:47:13 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> Change the default of LockingMode to LM_LIGHTWEIGHT from LM_LEGACY.
> 
> This fix has been tested with 3 Mach5 Tier[1-8] runs and a 4th is in process.

Looks good to me, thank you!

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Marked as reviewed by rkennke (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15797#pullrequestreview-1632446291