Fix bullet warnings in dashboard page

[rhian-cs]

Resolves #2373

Description

In the dashboard page, bullet was reporting some optimization to be done in the database queries that were used. I removed all of the warnings, by removing the unnecessary queries and adding the missing ones.

Type of change

• Tech debt

How Has This Been Tested?

For the bullet warnings themselves, I manually tested if the warnings still showed up in the dashboard.

bullet also supports a configuration that makes a spec fail if a bullet warning is raised:

# config/environments/development.rb
...
config.after_initialize do
  ...
  Bullet.raise = true
end

This could be useful in the future, but it can be kind of confusing for beginners and it would require fixing all of the bullet warnings first.

I also had to change a scope in the Donation model to add an includes call. To make sure this change was safe, I improved the tests for this scope.

Screenshots

No bullet warnings are shown anymore, yay \o/

[edwinthinks]

Thank you! This is great