Description

This PR follows up on changes made in gh-7350. Here's a small, point-wise summary noting the changes here:

• It updates the Emscripten/Pyodide CI job added in Add out-of-tree Pyodide builds in CI for scikit-image #7350 and removes the workaround JavaScript-based test suite file, since we fixed the s_cmp OpenBLAS unresolved symbol coming from SciPy upstream, having updated SciPy in-tree in Pyodide (see SciPy v1.13.0 pyodide/pyodide#4719, SciPy v1.14.0 pyodide/pyodide#5012, SciPy v1.14.1 pyodide/pyodide#5031, and more). This should make the testing slightly cleaner than before, and the test suite now runs till the end without any Pyodide fatal errors being reported.
  The Pyodide xbuildenv can now be used to set up a virtual environment in which the tests can be run in the same way they were before.
  The pyodide-build tool has been unvendored from the Pyodide repository and now infers the Pyodide version from the releases, downloading the relevant files from the GitHub release. Hence, the PYODIDE_VERSION environment variable is no longer required.
• There were some tests that have been failing on 32-bit platforms, which were last discussed quite a while ago: Multiple failures in 32-bit Linux builds #3091. They surprisingly passed in a WASM 32-bit environment here without issues, which is great. I have updated the skipping conditions to accommodate this.
• There's a known problem with the pytest bytecode generation when running the tests with the xbuildenv interpreter – I disabled the pytest internal cache plugin to fix that, but ignoring the warning (pyodide build failure pypa/cibuildwheel#1966 (comment)) works equally as well. Please let me know if there is a preference. :)

Additional context

• Pyodide CI support was first discussed in Build package for Pyodide out of tree #7265.
• At the time of writing, Pyodide 0.27alpha2 is used in the CI job; once 0.27 stable comes out (should be soon) and cibuildwheel updates to it, that (plus this PR) will help unblock another PR that I had opened a while back: Use cibuildwheel to build WASM/Pyodide wheels for scikit-image, push nightlies to Anaconda.org #7440. I can rebase that PR when ready.
• Fix dynamic library loading in cli runner pyodide/pyodide#4871 (comment)

Checklist

• A descriptive but concise pull request title
• Docstrings for all functions
• Unit tests
• A gallery example in ./doc/examples for new features
• Contribution guide is followed

Release note

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