feat: Add "became not consistent" memberactivity category

[amindadgar]

The became inconsistent or not consistent should be defined under the name of all_became_not_consistent and the definition is written below

Explanation for the activity type all_became_not_consistent, the people that were consistently active in the previous period but they aren't appearing in the consistent category again. this is representative of people inconsistently active in the last period.

The reason we chose not to use all_became_inconsistent is

Tjitse's message: I suggested the name change specifically to prevent people from thinking that all_became_inconsistent and all_inconsistent are related. You can become inconsistent either by starting to be active or by being consistent at first and then not being active anymore. all_became_inconsistent only logs the second group, the group that stopped being consistent