RFR: 8339238: Update to use jtreg 7.5.1 [v2]

[Christian Stein]

> Please review the change to update to using jtreg 7.5.1.
> 
> The primary change is to the `jib-profiles.js` file, which specifies the version of jtreg to use, for those systems that rely on this file. In addition, the `requiredVersion` has been updated in the various `TEST.ROOT` files.
> 
> Tested with tier 1 — tier 8.

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

  Update TEST.ROOT in `test/docs`

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20766/files
  - new: https://git.openjdk.org/jdk/pull/20766/files/8ed92e64..3a92207d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20766&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20766&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20766.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20766/head:pull/20766

PR: https://git.openjdk.org/jdk/pull/20766