RFR: 8287398: Allow concurrent execution of hotspot docker tests [v2]

[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.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  updated Common.imageName() to generate unique names

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8914/files
  - new: https://git.openjdk.java.net/jdk/pull/8914/files/65161a89..fe2c5c3c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8914&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8914&range=00-01

  Stats: 35 lines in 1 file changed: 26 ins; 1 del; 8 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