RFR: 8287398: Allow concurrent execution of hotspot docker tests

[Ioi Lam]

Remove the `exclusiveAccess.dirs=.` configuration (and thus the entire TEST.properties file) so that the  test/hotspot/jtreg/containers/docker/*.java tests can be executed concurrently. This reduces total execution from about 8 minuets to about 2.5 minuets on my machine.

In early days of JDK support for docker, we disabled concurrent execution as a precaution to avoid collisions in docker operations, such as building an image. Such collisions should no longer happen (each image is uniquely named).

In comparison, in tests/jdk/jdk/internal/platform/docker there are no such limitations, and the 6 docker tests there can be executed in parallel without issue.

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Commit messages:
 - 8287398: Allow concurrent execution of hotspot docker tests

Changes: https://git.openjdk.java.net/jdk/pull/8914/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8914&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287398
  Stats: 24 lines in 1 file changed: 0 ins; 24 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8914.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8914/head:pull/8914

PR: https://git.openjdk.java.net/jdk/pull/8914