RFR: 8267958: [TESTBUG] cds DynamicLoaderConstraintsTest.java timed out

[Ioi Lam]

[JDK-8267347](https://bugs.openjdk.java.net/browse/JDK-8267347) doubles the amount of time spent inside this test. It's better to split the test into two parts as suggested by @iignatev in https://github.com/openjdk/jdk/pull/4198#discussion_r641343393

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Commit messages:
 - [TESTBUG] cds DynamicLoaderConstraintsTest.java timed out

Changes: https://git.openjdk.java.net/jdk/pull/4287/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4287&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267958
  Stats: 57 lines in 2 files changed: 40 ins; 11 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4287.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4287/head:pull/4287

PR: https://git.openjdk.java.net/jdk/pull/4287