Feat: Collections on https://gitcoin.co/grants/ should be randomized

### User Story

As a user browsing the Grant applications, the collections displayed on https://gitcoin.co/grants/ and https://gitcoin.co/grants/explore/?tab=collections should be randomized to remove any bias.

At the same time, the user would would like having well thought out collections shown as well.

### Notes:

Right now it looks like we're prioritizing our own collections because they are sorted by descending ID.

### Definition of Done
[comment]: # (Any other information that would be useful, bullets are helpful.)

*GIVEN* I am on the collections tab on the Grants application home page
*WHEN* I am browsing the collections
*THEN* I see high quality, random collections shown to me.