Remove trim-one-to-one-rooms.js in favor of clean-up-users-old-one-to-one.js

Remove trim-one-to-one-rooms.js in favor of clean-up-users-old-one-to-one.js

Duplicated scripts:

• https://gitlab.com/gitlab-org/gitter/webapp/blob/1d5744b63c027716a5b18e50c035b20ac5e96b0b/scripts/utils/clean-up-users-old-one-to-one.js
• https://gitlab.com/gitlab-org/gitter/webapp/blob/1d5744b63c027716a5b18e50c035b20ac5e96b0b/scripts/utils/trim-one-to-one-rooms.js