[Cashtab] Remove extra space on eToken creation error msg

Summary: Removed extra space on eToken creation error message in Tokens.js. Related to task T2247.

Test Plan:
cd web/cashtab && npm start
Select a wallet with 0 XEC
navigate to tokens screen
ensure that the error message does not have a trailing space following the fiat symbol within the parentheses.

Reviewers: bytesofman, #bitcoin_abc

Reviewed By: bytesofman, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D11050