[crac] RFR: 8351402: [CRaC] Use System.nanoTime() in TimedWaitingTest [v2]

[Timofei Pushkin]

> Replaces `System.currentTimeMillis()` with `System.nanoTime()` in `TimedWaitingTest` since the former can, in theory, jump back and forth and that may lead to the test failures.
> 
> Also adds a diagnostic assert.

Timofei Pushkin has updated the pull request incrementally with one additional commit since the last revision:

  Fix time check

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

Changes:
  - all: https://git.openjdk.org/crac/pull/209/files
  - new: https://git.openjdk.org/crac/pull/209/files/2f1a1e14..53a2ec91

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=209&range=01
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=209&range=00-01

  Stats: 6 lines in 1 file changed: 3 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/crac/pull/209.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/209/head:pull/209

PR: https://git.openjdk.org/crac/pull/209