Replace jest-environment-jsdom with @jest/environment-jsdom-abstract (#46558)

Jest has introduced a package `@jest/environment-jsdom-abstract` that
can use a specified version of `jsdom` instead of being stuck with the
one it's bundled with. Let's use that.

Most of our projects were already using a customized environment anyway,
to work around jsdom not having `structuredClone`. Although most of
these still had an unused `jest-environment-jsdom` dep, probably from
before that was added.

A few for some reason weren't; those have been fixed (and redundant
`@jest-environment jsdom` comments have been removed).

Then have pnpm reject attempts to re-install `jest-environment-jsdom`,
so people don't accidentally re-add it.

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/20965650321

Upstream-Ref: Automattic/jetpack@f43a5ce

Author: anomiex

CHANGELOG.md

@@ -14,6 +14,9 @@ This is an alpha version! The changes listed here are not final.
 - Move publicize-components into publicize package.
 - Update package dependencies.
 
+### Removed
+- =
+
 ## [0.69.2] - 2026-01-12
 ### Changed
 - Update package dependencies. [#46456]