RFR: 8369423: Reduce execution time of testlibrary_tests/ir_framework/tests/TestDFlags.java

[Christian Hagedorn]

The test `testlibrary_tests/ir_framework/tests/TestDFlags.java` runs 11 separate IR framework runs by enabling only a single property/D flag in each run. This seems like a waste of resources for just a sanity run (we don't do any additional verification). Moreover, some newer property flags are missing.

I suggest to cut it down to 2 runs: 
- IR verification enabled (i.e. -DVerifyIR=true, which is the default) 
- IR verification disabled (i.e. -DVerifyIR=false)

In both runs we simultaneously set all property flags to some non-default value as a sanity test.

This reduces the test execution time from around 20-30s down to 3-4s.

Thanks,
Christian

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Commit messages:
 - 8369423: Reduce execution time of testlibrary_tests/ir_framework/tests/TestDFlags.java

Changes: https://git.openjdk.org/jdk/pull/27690/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27690&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369423
  Stats: 20 lines in 2 files changed: 7 ins; 3 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/27690.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27690/head:pull/27690

PR: https://git.openjdk.org/jdk/pull/27690