RFR: 8378854: Disable SA tests when ZGC is being used

[Chris Plummer]

We currently problem list all the SA tests when ZGC is being used. However, recently the CR they are problem listed under ([JDK-8307393](https://bugs.openjdk.org/browse/JDK-8307393)) was closed as WNF. Tests are not suppose to be problem listed under closed CRs. The proposed solution is to use the following in all the SA tests:

` * @requires vm.gc != "Z"`

Note I kept `serviceability/sa/TestUniverse.java` enabled for ZGC as it was explicitly called out in the problem list comment as a sanity check to keep enabled.

While adding the `@requires` I also did some minor cleanup in a few places to keep the `@requires` less cluttered and consistent between tests. Specifically I made it so `@requires vm.hasSA` is always on its own line and always first.

Testing in progress. Will cover all tier1 plus tier2, tier3, and tier5 svc testing.

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Commit messages:
 - disable SA tests when using ZGC
 - disable SA tests when using ZGC

Changes: https://git.openjdk.org/jdk/pull/29959/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29959&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378854
  Stats: 260 lines in 77 files changed: 94 ins; 91 del; 75 mod
  Patch: https://git.openjdk.org/jdk/pull/29959.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29959/head:pull/29959

PR: https://git.openjdk.org/jdk/pull/29959