[Feat.Req] Be more explicit about not running indexer-rs migrations and relying on indexer-agent

[gusinacio]

Problem statement
People are running the sqlx migrations and are getting problems with conflicts on the migrations.

Expectation proposal
Be more explicit on the documentation about not running the migrations using sqlx. They are handled by indexer-agent

[aasseman]

Seems the issue was not about running the sqlx migrations, but just migrating from indexer-agent v0.21 to the TAP version. We should test this scenario to make sure.