Migrate output_locking_bytecode_prefix_index to 35 bytes to cover entire locking bytecode for P2SH32

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Currently, search_output() won't appear to work for P2SH32 because no exact match will be found in the 25-byte index for 35-byte P2SH32 queries, even if the index contains the first 25 bytes of the matching result. We just need the next DB migration to extend that index from 25 bytes to 35 bytes to cover the whole length of P2SH32.

Current workaround is to simply use search_output_prefix() rather than search_output() for P2SH32 queries, but in the long term, we should migrate the index to avoid new users having to understand what's happening here.