## What changed?

We now specify `interpolateParams` by default when using MySQL for our
main.

While we don't currently support specifying `interpolateParams` for
MySQL visibility databases, I changed the type returned when serializing
`VisibilitySearchAttributes` as a first step towards doing so (MySQL 8
won't allow binary data within JSON columns, which makes sense).

While we could also have explicitly prepared and reused our statements
that requires far more work and it may not be the better approach
anyways.

## Why?

@mattrobenolt did a good job of explaining why in #5425 but I'll
summarize it here anyways.

When `interpolateParams` is false (the default) the driver will prepare
parameterized statements before executing them, meaning we need two
round-trips to the database for each query. By setting
`interpolateParams` to true the DB driver will handle interpolation and
send the query just once to the database, halving the number of round
trips necessary. This should improve the performance of all clusters
using MySQL.

## How did you test it?
Existing tests.

## Potential risks
No

## Is hotfix candidate?
This is up for discussion