crypto: harden WebCrypto jobs and promise handling #7075

Job	Run time
Build slim tarball	1m 54s
aarch64-linux: Cache V8 build	24s
x86_64-linux: with shared libraries	28m 13s
aarch64-darwin: with shared libraries	27m 33s
x86_64-darwin: with shared libraries	37m 52s
aarch64-linux: with shared openssl-3.5.5	24m 8s
aarch64-linux: with shared boringssl-0.20260413.0	23m 29s
aarch64-linux: with shared openssl-1.1.1w	23m 11s
aarch64-linux: with shared openssl-4.0.0	23m 33s
aarch64-linux: with shared openssl-3.6.1	23m 31s
aarch64-linux: with shared openssl-3.0.19	25m 21s
	3h 59m 9s

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