[CI] Templatize the js mocha projects unit tests

Summary: It avoids copy paste errors and facilitates the maintenance.

Test Plan:

./contrib/teamcity/build-configurations.py alias-server-tests
./contrib/teamcity/build-configurations.py ecash-herald-tests

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D13648