RFR: 8369456: [TESTBUG] Fix the test failure of TestSelectFromTwoVectorOp.java on sve2 platforms

[erifan]

According the AD file, partial cases where `vector_length_in_bytes > 8` of the vector API `selectFrom` are not supported on the AArch64 SVE2 platform. But the test `TestSelectFromTwoVectorOp.java` didn't rule out these cases, leading to test faiulres on sve2 plaftforms where `MaxVectorSize > 16`.

This test problem was discovered by simulating a 512-bit sve2 environment using qemu.

This PR fixes these test failures.

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Commit messages:
 - 8369456: [TESTBUG] Fix the test failure of TestSelectFromTwoVectorOp.java on sve2 platforms

Changes: https://git.openjdk.org/jdk/pull/27723/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27723&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369456
  Stats: 62 lines in 3 files changed: 40 ins; 1 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/27723.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27723/head:pull/27723

PR: https://git.openjdk.org/jdk/pull/27723