RFR: 8269077: TestSystemGC uses @require vm.gc.G1 for large pages subtest

[Stefan Karlsson]

The invocation that runs with large pages are guarded with @requires vm.gc.G1 and doesn't explicitly state that G1 should be used.

This means two things:
1) We are not running the large pages subtest when other GCs are specified
2) Under some circumstances another GC is ergonomically selected and we run the test with that GC even though the test was guarded by @require vm.gc.G1.

I propose that we move the subtest to its own run section, without any requirement about the used GC.

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Commit messages:
 - 8269077: TestSystemGC uses @require vm.gc.G1 for large pages subtest

Changes: https://git.openjdk.java.net/jdk/pull/4538/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4538&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269077
  Stats: 9 lines in 1 file changed: 7 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4538.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4538/head:pull/4538

PR: https://git.openjdk.java.net/jdk/pull/4538