RFR: 8343345: Use -jvmArgsPrepend when running microbenchmarks in RunTests.gmk

[Chen Liang]

On Thu, 31 Oct 2024 08:53:07 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> Update RunTests.gmk to use `-jvmArgsPrepend` to avoid overwriting built-in micro `jvmArgs` flags.

Makes sense. Should be safe since we no longer have explicit prepend args, and make only exposes this one option for VM args.

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Marked as reviewed by liach (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21800#pullrequestreview-2408064251