fix(abstract-substrate): blake2_256 prehash signablePayload over 256 bytes #3526

Job	Run time
Generate head API spec	7m 37s
Generate merge base API spec	8m 17s
Check specs identical	6s
API Spec Check	4s
Generate vacuum reports for API spec	0s
Check breaking changes	0s
Linter Override	0s
	16m 4s

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