[e.cash] Remove guarda wallet from /wallets

Summary: Was requested to remove Guarda wallet from /wallets due to issues with their eCash wallet

Test Plan: Preview the site and check the /wallets page renders correct and Guarda wallet is gone

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14904