[Cashtab][Alias] Remove redundant node error translation in handleAliasRegistrationError

Summary:
T3316

The 'too many unconfirmed ancestors' node error is no longer applicable in handleAliasRegistrationError, hence removing the error translation logic.

Test Plan:
Attempt to register a new alias on a wallet with insifficient funds and ensure the node error is rendered as a UI pop up
grep -r handleAliasRegistrationError src/

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14638