Moved the issue boards card template into the JS. This helps to improve
the code coverage & will eventually make it easier to move this to .vue
files

When dragging an issue to a list that it already exists in it was previously not removing the label for the list it was moving from. This changes that to make that API call.

Closes #28484

Added some error handling which reverts the frontend data changes &
notifies the user

Does not remove the issue from the selected tab when it it de-selected, it instead gets purged when changing tab

expand remaining non-explicit eslint-disable blocks and factor out globals when no-undef encountered

Only visible when scrollable area is larger than height

Closes #21139

Fixed JS tests