Declare and use NonHardenedChildIndex for transparent #4589

Job	Run time
Clippy (MSRV)	4m 14s
Build target wasm32-wasi	3m 43s
Bitrot check	4m 22s
Latest build on ubuntu-latest	1m 55s
Clippy (beta)	16s
Code coverage	20m 32s
Latest build on windows-latest	4m 34s
Intra-doc links	4m 46s
Latest build on macOS-latest	4m 35s
Rustfmt	14s
protobuf consistency	4m 4s
Test on ubuntu-latest	12m 28s
UUID validity	2s
Test on ubuntu-latest with --features orchard	12m 37s
Test on ubuntu-latest with --features unstable-nu6	12m 37s
Test on ubuntu-latest with --features zfuture	13m 10s
Test on windows-latest	17m 20s
Test on windows-latest with --features orchard	16m 49s
Test on windows-latest with --features unstable-nu6	17m 18s
Test on windows-latest with --features zfuture	17m 19s
Test on macOS-latest	18m 14s
Test on macOS-latest with --features orchard	16m 13s
	3h 27m 22s

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