Rust: remove shipped feature flag #10011

Job	Run time
analyze-actions	1m 1s
check-codeql-versions	42s
analyze-javascript (ubuntu-22.04, linked)	4m 8s
analyze-javascript (ubuntu-24.04)	4m 11s
analyze-javascript (ubuntu-22.04)	3m 56s
analyze-javascript (windows-2022)	5m 58s
analyze-javascript (ubuntu-24.04, linked)	4m 14s
analyze-javascript (windows-2022, linked)	5m 53s
analyze-javascript (windows-2025, linked)	6m 45s
analyze-javascript (macos-13, linked)	9m 44s
analyze-javascript (macos-13)	6m 32s
analyze-javascript (macos-15)	6m 36s
analyze-javascript (windows-2025)	5m 43s
analyze-javascript (macos-15, linked)	7m 20s
analyze-javascript (macos-14)	5m 26s
analyze-javascript (macos-14, linked)	5m 38s
	1h 23m 47s

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