crypto: harden WebCrypto jobs and promise handling #6857

Job	Run time
Build slim tarball	1m 55s
aarch64-linux: Cache V8 build	21s
x86_64-linux: with shared libraries	31m 16s
x86_64-darwin: with shared libraries	37m 13s
aarch64-darwin: with shared libraries	26m 34s
aarch64-linux: with shared boringssl-0.20260413.0	26m 31s
aarch64-linux: with shared openssl-3.6.1	25m 55s
aarch64-linux: with shared openssl-3.0.19	26m 44s
aarch64-linux: with shared openssl-4.0.0	25m 52s
aarch64-linux: with shared openssl-3.5.5	26m 12s
aarch64-linux: with shared openssl-1.1.1w	25m 57s
	4h 14m 30s

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