This fixes the fact that these emoji were sometimes not displaying
properly (because of changes in the emoji names used in the codebase),
while also making this integration more standard (since it was the
only one with such an aggressive use of emoji).
This commit adds a test for the payload that is generated when
a Task is moved from one user story to another on Taiga's Sprint
Taskboard UI.
This commit also gets up this webhook's test coverage up to 100%.
I dug into why we never did this before, and it turns out we did, but
using `$.trim()` (which removes leading whitespace as well!). When
removing the `$.trim()` usage.
Fixes#3294.