Investigate excluding bugs that received no updates after a component was assigned by bugbot from the training set of the component model

[marco-c]

For badly triaged components, there is a risk that bugbot moves a bug to the component and then nobody moves it to a better place. Over time, this can bias the training set as we wrongly add more and more bugs to those components.

We should investigate how frequently bugbot wrongly moved a bug to a component, and then the bug didn't receive any meaningful updates.