RFR: 8350159: compiler/tiered/Level2RecompilationTest.java fails after JDK-8349915

[Aleksey Shipilev]

Recently added hunk in `CompilationPolicy::selected_task` was supposed to target CTW runs, that wanted to omit any level changes. But there are tests that _do test_ level changes, and they submit `Whitebox` requests. One of those tests is `compiler/tiered/Level2RecompilationTest.java`. So it looks like we need to disambiguate the "CTW" uses and "general Whitebox" uses.

Looks like checking for `-Xbatch` does the trick for CTW. It is not super-clean, but it works, and it matches other exceptions in around compilation policy, e.g. when checking for `-Xcomp`, etc.

Additional testing: 
 - [x] Linux AArch64 server fastdebug, `compiler/tiered/Level2RecompilationTest.java` now passes
 - [x] Linux AArch64 server fastdebug, CTW tests still work fine
 - [ ] Linux AArch64 server fastdebug, `all`

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/23668/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23668&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350159
  Stats: 5 lines in 2 files changed: 0 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23668.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23668/head:pull/23668

PR: https://git.openjdk.org/jdk/pull/23668