rune: Clean up tests #1849

Job	Run time
msrv	1m 47s
clippy	2m 4s
nightly	3m 38s
docs	3m 17s
rustfmt	14s
basics	1s
wasm	1m 13s
no_std (ubuntu-latest, minimal)	1m 3s
build_feature (alloc)	3m 19s
test_doc	6m 16s
no_std (macos-latest, minimal)	1m 57s
test_lib	4m 44s
build_feature (cli)	4m 9s
build_feature (cli,doc)	4m 20s
test_miri (rune)	3m 42s
test_rune	3m 0s
build_feature (cli,fmt)	4m 18s
test_miri (rune-core)	41s
build_feature (doc)	3m 45s
test_miri (rune-alloc)	6m 9s
build_feature (workspace)	3m 28s
build_feature (languageserver)	3m 55s
build_feature (byte-code)	3m 32s
build_feature (capture-io)	3m 33s
build_feature (emit)	3m 37s
	1h 17m 42s

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