Remove `Send + Sync` bounds when `no-std` #20825

Job	Run time
coverage	19m 15s
ext-test	7m 0s
build (self-hosted, stable)	1h 43m 22s
build (self-hosted, 1.75.0)	1m 15s
build (windows-latest, stable)	2h 6m 26s
build (self-hosted, beta)	2h 28m 52s
build (macos-latest, stable)	1h 34m 14s
build (macos-latest, 1.75.0)	1m 1s
check_release	2m 12s
benchmark	16m 57s
build-tx-sync (ubuntu-latest, stable)	4m 46s
linting	2m 25s
build-tx-sync (ubuntu-latest, beta)	4m 29s
build-tx-sync (macos-latest, stable)	7m 5s
build-tx-sync (macos-latest, 1.75.0)	8m 34s
build-tx-sync (ubuntu-latest, 1.75.0)	5m 15s
rustfmt	16s
build-tx-sync (macos-latest, beta)	8m 15s
fuzz	3h 46m 6s
check_docs	4m 5s
	13h 11m 50s

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