RFR: 8342958: Use jvmArgs consistently in microbenchmarks

[Claes Redestad]

Many OpenJDK micros use `@Fork(jvmArgs/-Append/-Prepend)` to add JVM reasonable or necessary flags, but when deploying and running micros we often want to add or replace flags to tune to the machine, test different GCs, etc. The inconsistent use of the different `jvmArgs` options make it error prone, and we've had a few recent cases where we've not been testing with the expected set of flags. 

This PR suggests using `jvmArgs` consistently. I think this aligns with the intuition that when you use `jvmArgsAppend/-Prepend` intent is to add to a set of existing flags, while if you supply `jvmArgs` intent is "run with these and nothing else". Perhaps there are other opinions/preferences, and I don't feel strongly about which to consolidate to as long as we do so consistently. One argument could be made to consolidate on `jvmArgsAppend` since that one is (likely accidentally) the current most popular (143 compared to 59 `jvmArgsPrepend` and 18 `jvmArgs`).

-------------

Commit messages:
 - Change all micros to consistently use jvmArgs, leaving both jvmArgsAppend/-Prepend free for ops

Changes: https://git.openjdk.org/jdk/pull/21683/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21683&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342958
  Stats: 202 lines in 142 files changed: 0 ins; 0 del; 202 mod
  Patch: https://git.openjdk.org/jdk/pull/21683.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21683/head:pull/21683

PR: https://git.openjdk.org/jdk/pull/21683