Remove unsound `SendSyncWrapper` #5178

Job	Run time
Check formatting	7s
Run cargo-deny on Android	23s
Run cargo-deny on iOS	21s
Run cargo-deny on Linux	22s
Test stable Windows 64bit MSVC	2m 13s
Run cargo-deny on macOS	22s
Test stable Windows 32bit MSVC	2m 45s
Test stable Windows 64bit GNU	2m 11s
Run cargo-deny on Redox OS	22s
Test stable Windows 32bit GNU	2m 17s
Run cargo-deny on web	21s
Test stable Linux 32bit	3m 0s
Run cargo-deny on Windows	20s
Test stable Linux 64bit	2m 38s
Test stable X11	2m 20s
Test stable Wayland	2m 16s
Test stable Android	51s
Test stable Redox OS	22s
Test stable macOS	1m 42s
Test stable iOS x86_64	1m 17s
Test stable iOS Aarch64	1m 16s
Test stable web	59s
Test nightly Windows 64bit MSVC	1m 42s
Test nightly Windows 32bit MSVC	2m 7s
Test nightly Windows 64bit GNU	2m 5s
Test nightly Windows 32bit GNU	2m 11s
Test nightly Linux 32bit	2m 35s
Test nightly Linux 64bit	2m 19s
Test nightly X11	2m 20s
Test nightly Wayland	2m 17s
Test nightly Android	1m 0s
Test nightly Redox OS	17s
Test nightly macOS	1m 58s
Test nightly iOS x86_64	1m 52s
Test nightly iOS Aarch64	1m 10s
Test nightly web	54s
Test 1.70.0 Windows 64bit MSVC	50s
Test 1.70.0 Windows 32bit MSVC	53s
Test 1.70.0 Windows 64bit GNU	1m 7s
Test 1.70.0 Windows 32bit GNU	1m 13s
Test 1.70.0 Linux 32bit	1m 16s
Test 1.70.0 Linux 64bit	55s
Test 1.70.0 X11	42s
Test 1.70.0 Wayland	44s
Test 1.70.0 Redox OS	25s
Test 1.70.0 macOS	1m 3s
Test 1.70.0 iOS x86_64	42s
Test 1.70.0 iOS Aarch64	47s
Test 1.70.0 web	42s
Test 1.70.0 Android	37s
	1h 5m 28s

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