RFR: 8303417: RISC-V: Merge vector instructs with similar match rules

[Yanhong Zhu]

Merge vector instructs with similar match rules in riscv_v.ad.

Tier 1~3 passed on QEMU with RVV supported.

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Commit messages:
 - merge vector instructs with same match rule

Changes: https://git.openjdk.org/jdk/pull/14214/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14214&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303417
  Stats: 504 lines in 1 file changed: 33 ins; 379 del; 92 mod
  Patch: https://git.openjdk.org/jdk/pull/14214.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14214/head:pull/14214

PR: https://git.openjdk.org/jdk/pull/14214