[Cashtab][Alias] Deprecate getAliasServerState

Summary:
T3216

Following the removal of the /state endpoint on the alias-server, the getAliasServerState function is no longer in use.

Test Plan:
grep -r getAliasServerState src/
npm test

Reviewers: bytesofman, #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14319