Force legacy crypto for loading tests

[BillCarsonFr]

The loading-test.tsx only runs correctly on legacy crypto. They are running a mix of localStorage and indexeddb storage (partial mock of indexeddb through the all stack), and also they are running without crypto (by not loading libolm). The rust sdk doesn't work this way, it's using indexeddb to store things and cannot be disabled by not loading a lib.

Checklist

• Tests written for new code (and old code if feasible)
• Linter and other CI checks pass
• Sign-off given on the changes (see CONTRIBUTING.md)

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This change is marked as an internal change (Task), so will not be included in the changelog.

[andybalaam]

Quoting @richvdh from a private Matrix room:

loading-test.tsx are mostly some application-level tests that I wrote back in 2016, and they attempt to test some of the startup flows in EW (as the comment says, though it hasn't been updated when the file was renamed). I don't think they offer a huge amount of value, and what little value they do offer would be better done in playwright anyway. #26954 seems like a good stopgap.

So I agree - this change keeps these tests running as they were, but they don't provide enough value to try to port them to Rust, certainly not to gate our Element Web R release behind making them work with Rust.