[jdk8u-dev] RFR: 8317374: Add Let's Encrypt ISRG Root X2 [v2]

[Severin Gehwolf]

> Backport so as to add the Let's Encrypt ISRG Root X2 CA. Applies clean after path shuffeling. Please review!
> 
> Testing:
> - [ ] GHA (still running)
> - [x] `jdk/test/security/infra/java/security/cert/CertPathValidator` and  `jdk/test/sun/security/lib/cacerts` jtreg tests.

Severin Gehwolf 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.

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Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/398/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/398/files/71a0adac..71a0adac

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=398&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=398&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/398.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/398/head:pull/398

PR: https://git.openjdk.org/jdk8u-dev/pull/398