Make it clearer that another issue tracker is enabled

Problem

Currently, it's not clear that only one issue tracker integration can be enabled at once. There are some cases where it is possible to enable multiple trackers at once which results in errors and the inability to disable them correctly.

Proposal

• When an integration issue tracker is enable, display a non-dismissable alert on all other issue tracker integration configuration views.

Alert UI text:

Another issue tracker is already in use
Only one issue tracker service can be active at a time. Please disable the active tracker first and try again.

Current	Proposal