ci: Use dtolnay/rust-toolchain consistently

[ok-nick]

Removes usage of actions-rust-lang/setup-rust-toolchain and replaces it with dtolnay/rust-toolchain and Swatinem/rust-cache that we normally use. Potentially fixes a previously reported issue with intermittent errors building the Android libraries.

[codspeed-hq]

CodSpeed Performance Report

Merging #1622 will not alter performance

_{Comparing ok-nick/ci-rust-toolchain (6500083) with main (629ab6e)}

Summary

✅ 16 untouched
⏩ 2 skipped¹

Footnotes

1. 2 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[tmathern]

(I think a job from the PR checks has decided to hang, or is very, very, very slow to complete and clean up)