feat: Add "became unvital" memberactivity category

[amindadgar]

The became unvital should be defined under the category all_became_unvital in analytics pipeline and the definition of it is written below

Explanation for the activity type all_became_unvital, is people were vital in the past period but they aren't vital now (either they haven't been active or they haven't been connected at least to 5 people).