Rust optimizer improvements #4173

Job	Run time
Check for upstream trigger phrase	3s
Build & Test (ubuntu-latest, python: 3.8, distributed: false)	8m 25s
Test importing with bare requirements	12m 30s
Build & Test (ubuntu-latest, python: 3.9, distributed: false)	9m 21s
Build & Test (ubuntu-latest, python: 3.10, distributed: false)	9m 25s
Build & Test (windows-latest, python: 3.8, distributed: false)	26m 15s
Build & Test (windows-latest, python: 3.9, distributed: false)	17m 23s
Build & Test (windows-latest, python: 3.10, distributed: false)	18m 27s
Build & Test (macos-latest, python: 3.8, distributed: false)	14m 26s
Build & Test (macos-latest, python: 3.9, distributed: false)	18m 44s
Build & Test (macos-latest, python: 3.10, distributed: false)	18m 0s
Build & Test (ubuntu-latest, python: 3.8, distributed: true)	13m 50s
Build & Test (ubuntu-latest, python: 3.10, distributed: true)	9m 24s
	2h 56m 13s

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