fix: Stop importing the generated test-utils barrel from two wrappers

[TrevorBurnham]

While working on #4948, I noticed that the ban-files rule defined in the build-tools repo has a bug that's causing it to miss two existing violations in this repo. This PR fixes those violations, before I fix the rule itself.

The violation

src/test-utils/dom/index.ts imports every component wrapper. A wrapper importing it back is therefore circular, which is what ban-files is configured to prevent. The two import createWrapper from '../index.js' lines removed by this PR should have triggered a rule violation like this:

Do not import from the augmented ElementWrapper barrel 'src/test-utils/dom/index.ts'.
Use @cloudscape-design/test-utils-core/dom instead.

The reason they didn't trigger it is that they include the .js extension, which ban-files doesn't expect. The rule only probed extensions appended to the literal path, so it tested src/test-utils/dom/index.js and src/test-utils/dom/index.js.ts rather than matching the banned src/test-utils/dom/index.ts.

The fix

@cloudscape-design/test-utils-core already exports createWrapper from both its /dom and /selectors entry points, and its implementation is the same one the generated barrel copies:

// test-utils-core/dom            // the generated barrel
createWrapper(root = document.body)   wrapper(root: Element = document.body)

So swapping the import is behaviour-identical, and the call sites are untouched. Importing from test-utils-core/dom also means the selectors converter rewrites the path to /selectors for free, so the generated selectors output stops importing its barrel too.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.76%. Comparing base (dec0201) to head (e005fcd).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4949      +/-   ##
==========================================
- Coverage   97.66%   93.76%   -3.91%     
==========================================
  Files         959      958       -1     
  Lines       31342    27136    -4206     
  Branches    11577     9761    -1816     
==========================================
- Hits        30611    25443    -5168     
+ Misses        724      613     -111     
- Partials        7     1080    +1073     

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