fix: zero points showing for all contributors

[StephZam]

Fixes #671

[rithviknishad]

@StephZam could you go through this entire queries.ts file and figure out which all other queries also have this issue? 🤔

When doing SELECT with points on activity table, can we coalesce in all such places?

For example:

activityQueries.getAll, activityQueries.getByContributor and all have this issue right?

One of the query here is affecting the aggregate computation of total points of contributors (which would be shown in each the contributor's profile page).

Also update the tests as well to assert edge cases of these... We have quite good amount of tests already written, let's continue improving it.