Removes duplicate trivia from UnsafeExprSyntax #145

Job	Run time
Run tests using swift-syntax-dev-utils (Linux)	22m 54s
Validate generated code	2m 45s
Run tests using swift-syntax-dev-utils (Windows)	46m 22s
Test / Linux (5.9 - jammy)	3m 52s
Test / Windows (5.9 - windows-2022)	23m 37s
Test / Linux (5.10 - jammy)	3m 50s
Test / Windows (6.0 - windows-2022)	21m 37s
Test / Linux (6.0 - jammy)	4m 5s
Test / Linux (6.1 - jammy)	3m 59s
Test / Windows (6.1 - windows-2022)	22m 2s
Test / Linux (nightly-main - jammy)	4m 47s
Test / Windows (nightly - windows-2019)	16m 17s
Test / Linux (nightly-6.1 - jammy)	4m 51s
Test / Windows (nightly-6.1 - windows-2019)	15m 28s
Soundness / Documentation check	4m 57s
Soundness / API breakage check	0s
Soundness / Broken symlinks check	6s
Soundness / Format check	35s
Soundness / License headers check	11s
Soundness / Shell check	32s
Soundness / Unacceptable language check	4s
Soundness / Python lint check	4s
Soundness / YAML lint check	6s
	3h 23m 1s

Provide feedback