RFR: 8333358: java/io/IO/IO.java test fails intermittently [v4]

[Pavel Rappo]

> Please review this fix for an intermittent test failure.
> 
> On some configurations, the default `expect` timeout of 10 seconds is insufficient. It is increased to 20; it's hard to imagine a configuration for which that new value would still be insufficient, but we'll see.
> 
> Aside from that, test-generated diagnostics are improved: the version of the `expect` command and the duration of each test method are recorded. `output.exp` is modified for robustness and clear indication of the timeout condition.
> 
> I was reminded, out-of-band, that test timeouts should be scaled with `test.timeout.factor`. I propose to integrate this PR first and then separately update all the affected tests to scale their `expect` timeouts.

Pavel Rappo has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge branch 'master' into 8333358
 - Add a comment for future maintainers
 - Disable timeout in expect scripts
 - Change url as suggested in review
 - Initial commit

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19627/files
  - new: https://git.openjdk.org/jdk/pull/19627/files/56d24203..aad8b491

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19627&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19627&range=02-03

  Stats: 12646 lines in 467 files changed: 4452 ins; 7038 del; 1156 mod
  Patch: https://git.openjdk.org/jdk/pull/19627.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19627/head:pull/19627

PR: https://git.openjdk.org/jdk/pull/19627