Fixes #27494
When the -signetchallenge argument is provided, the hash-160 of the challenge is appended to the data directory name. This ensures that each signet has its own distinct data directory, following the naming convention signet_XXXXXXX.
Note: The behaviour of the default signet remains unchanged
Update:
When the -signetchallenge argument is provided, the first 8 characters of the hash-160 of the challenge are appended to the data directory name. This ensures that each signet has its own distinct data directory, following the naming convention signet_XXXXXXX.