Preload kaminari collections to avoid counting

[compactcode]

Why

The goal of this change is to avoid doing a COUNT(*) when paginating a query with only one page of results.

This is important to us because we are running a large postgres database where COUNT(*) tends to add significant overhead on our larger multi-gigabyte tables.

What

• Kaminari contains logic to avoid doing a count when on last page of a query.
• We can leverage this logic by preloading activerecord relations before attempting to paginate.

Assumptions

This PR is built on the assumption that we will always be loading the relation we are paginating.

Before

With a search that returns 2 results:

(159.6ms)  SELECT COUNT(DISTINCT "contacts"."id") FROM "contacts ...
Contact Load (183.1ms)  SELECT DISTINCT "contacts"."id" ...

After

With a search that returns 2 results:

Contact Load (158.2ms)  SELECT DISTINCT "contacts"."id" ...

With a search that returns 2 results and a page size of 1 we still get the COUNT:

Contact Load (203.2ms)  SELECT DISTINCT "contacts"."id"...
(170.6ms)  SELECT COUNT(DISTINCT "contacts"."id") FROM "contacts"...

[trev]

Ping @davidcelis

[zubin]

Ping @davidcelis

Any chance of merging this or providing feedback? 🙏