uucore: disable default signal-handlers added by Rust #18430

Job	Run time
Style/cargo-deny	1s
Documentation/warnings (ubuntu-latest, feat_os_unix)	1s
MinRustV (ubuntu-latest, feat_os_unix)	1s
Code Coverage (ubuntu-latest, unix, nightly)	1s
Dependencies (ubuntu-latest, feat_os_unix)	1s
Code Coverage (macos-latest, macos, nightly)	1s
Style/deps (ubuntu-latest, feat_Tier1,feat_require_unix,feat_require_unix_utmpx)	1s
Style/deps (macos-latest, feat_Tier1,feat_require_unix,feat_require_unix_utmpx)	1s
Separate Builds (ubuntu-latest)	1s
Style/deps (windows-latest, feat_os_windows)	1s
Separate Builds (macos-latest)	1s
Separate Builds (windows-latest)	1s
Build	1s
Build/Makefile	1s
Build/nightly	1s
Build/stable	1s
Binary sizes	1s
Tests/BusyBox test suite	1s
Tests/Toybox test suite	1s
	19s

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