RFR: 7903961: Make default timeout configurable [v3]

[Christian Stein]

> Please review this change replacing the hard-coded `120` seconds default timeout for test actions with a configurable solution parsing a custom default value from `TEST.ROOT` and `TEST.properties` files:
> 
> 
> timeout.default.seconds=360
> 
> 
> Especially in combination with "JUnit.dirs" and "TestNG.dirs", where all actions directives found in a test file are ignored, is helpful.

Christian Stein has updated the pull request incrementally with one additional commit since the last revision:

  Add default timeout self-test

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Changes:
  - all: https://git.openjdk.org/jtreg/pull/253/files
  - new: https://git.openjdk.org/jtreg/pull/253/files/b9c04050..4cc80531

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=253&range=02
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=253&range=01-02

  Stats: 160 lines in 7 files changed: 160 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jtreg/pull/253.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/253/head:pull/253

PR: https://git.openjdk.org/jtreg/pull/253