Two fixes related to main graph and revenue metrics (#6331)

* organize QueryBuilder.do_build function better

* fix querying revenue metrics when including imports

* Invalidate queries where the only (revenue) metric is dropped

This fixes a 500 error where we're trying to optimistically fetch the
main graph with a stored revenue metric, while the goal filter has been
removed.

Rather than dropping revenue metrics in QueryOptimizer (which does not
validate anything), we will do it in QueryBuilder instead. Query building
will fail when dropping revenue metrics leaves query.metrics empty.

* add moduledoc to silence credo

* pattern match + guard to avoid nested if

* ParsedQueryParams.to_query!

* fix reading relative_date

* cleaner with Map.from_struct