[tg bot] use token instead of etoken in variables

Summary:
T2972

Depends on D13281

When it comes to camel case variable naming, ambiguity sometimes can arise between the use of 'etoken' and 'eToken'. To remove this problem, just use 'token' in variable names. Use 'eToken' in user-facing strings.

Test Plan:
In parse.js, ctrl+f 'etoken', only results are strings and not variable names
npm test
npm run msgs

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D13282