RFR: 8336753: Don't run serviceability/sa/ClhsdbDumpheap.java with -Xcomp [v2]

[Daniel Lundén]

> We are seeing quite a few timeouts for `serviceability/sa/ClhsdbDumpheap.java` running with -Xcomp in testing, possibly related to [JDK-8324241](https://bugs.openjdk.org/browse/JDK-8324241). We should disable running `ClhsdbDumpheap.java` with -Xcomp, at least for now.
> 
> ### Changeset
> 
> - Add `@requires vm.compMode != "Xcomp"` to `ClhsdbDumpheap.java`.

Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:

  Add comment and bug number

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20237/files
  - new: https://git.openjdk.org/jdk/pull/20237/files/e3aa2a73..2648fab2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20237&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20237&range=00-01

  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20237.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20237/head:pull/20237

PR: https://git.openjdk.org/jdk/pull/20237