Removes duplicate trivia from UnsafeExprSyntax #151

Job	Run time
Run tests using swift-syntax-dev-utils (Linux)	23m 26s
Run tests using swift-syntax-dev-utils (Windows)	45m 18s
Validate generated code	2m 51s
Test / Linux (5.9 - jammy)	3m 57s
Test / Windows (5.9 - windows-2022)	22m 11s
Test / Linux (5.10 - jammy)	3m 52s
Test / Windows (6.0 - windows-2022)	30m 0s
Test / Linux (6.0 - jammy)	4m 9s
Test / Windows (6.1 - windows-2022)	19m 38s
Test / Linux (6.1 - jammy)	4m 9s
Test / Windows (nightly - windows-2019)	16m 2s
Test / Linux (nightly-main - jammy)	4m 35s
Test / Windows (nightly-6.1 - windows-2019)	15m 52s
Test / Linux (nightly-6.1 - jammy)	4m 54s
Soundness / API breakage check	0s
Soundness / Documentation check	5m 20s
Soundness / Broken symlinks check	5s
Soundness / License headers check	12s
Soundness / Format check	41s
Soundness / Python lint check	7s
Soundness / Shell check	35s
Soundness / Unacceptable language check	5s
Soundness / YAML lint check	3s
	3h 28m 2s

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