[e.cash] Remove env vars from repo

Summary: removing the GA id and weglot key from this public repo to instead be inserted in the CI build

Test Plan:
preview the site and everything should function as before but GA and weglot will have undefined for their id values
You should see some text in the top right explaining this if they are absent

Reviewers: #bitcoin_abc, bytesofman, Fabien

Reviewed By: #bitcoin_abc, bytesofman, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14358