Rust optimizer improvements #4194

Job	Run time
Check for upstream trigger phrase	5s
Test importing with bare requirements	6m 31s
Build & Test (ubuntu-latest, python: 3.8, distributed: false)	5m 43s
Build & Test (ubuntu-latest, python: 3.9, distributed: false)	5m 33s
Build & Test (ubuntu-latest, python: 3.10, distributed: false)	5m 58s
Build & Test (windows-latest, python: 3.8, distributed: false)	6m 11s
Build & Test (windows-latest, python: 3.9, distributed: false)	6m 14s
Build & Test (windows-latest, python: 3.10, distributed: false)	5m 35s
Build & Test (macos-latest, python: 3.8, distributed: false)	6m 36s
Build & Test (macos-latest, python: 3.9, distributed: false)	6m 37s
Build & Test (macos-latest, python: 3.10, distributed: false)	6m 36s
Build & Test (ubuntu-latest, python: 3.8, distributed: true)	5m 40s
Build & Test (ubuntu-latest, python: 3.10, distributed: true)	5m 52s
	1h 13m 11s

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