chore: delete old VirtualArray class

[ikrommyd]

Since the next release will be a minor version bump, we just delete the old deprecated VirtualArray class

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.65%. Comparing base (02d8408) to head (6d3e6d3).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

Files with missing lines	Coverage Δ
src/awkward/_nplikes/virtual.py	92.11% <ø> (+1.25%)	⬆️

... and 2 files with indirect coverage changes

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

The documentation preview is ready to be viewed at http://preview.awkward-array.org.s3-website.us-east-1.amazonaws.com/PR3848

[ikrommyd]

The gpu cudf failures are for #3847 to fix so I'll just merge here since gpu tests are not required to pass.