RFR: 8344371: RISC-V: compiler/intrinsics/chacha/TestChaCha20.java fails after JDK-834355

[Fei Yang]

>From the error message, the cause of the failure is that 'UseRVV' was made diagnostic in [JDK-8343555](https://bugs.openjdk.org/browse/JDK-8343555). But the test was not updated to refect this. Instead of adding one extra `-XX:+UnlockDiagnosticVMOptions` option, this simply removed the use of `-XX:+UseRVV` from the test. The reason is that we have `-XX:+UseRVV` auto detected and enabled, so we will have RVV extension if we satisfy the test requirement:

(os.arch == "riscv64" & vm.cpu.features ~= ".*rvv.*")


Same test pass with this fix on linux-riscv64 with RVV extension.

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Commit messages:
 - 8344371: RISC-V: compiler/intrinsics/chacha/TestChaCha20.java fails after JDK-8343555

Changes: https://git.openjdk.org/jdk/pull/22188/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22188&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344371
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22188.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22188/head:pull/22188

PR: https://git.openjdk.org/jdk/pull/22188