Fix bug in selectCountDocs

The refactored DB API now has a separate building block to create an Opaleye query that
counts the number of returned results; we do that via `countRows`, exactly like the previous version.

However, I have discovered a small footgun in the Opaleye API -- if you have
two `Select` statements both calling countRows in a chain, that will always yield a value of 1,
because the inner `countRows` will give you the actual number of results by returning
a single row with an integer inside (i.e. the count).

However, the subsequent (outer) call to `countRows` will return the number of rows
of the previous step .. which is always going to be one!

The bug was that I had left somewhere the spurious `countRows` in the query which
would return the number of documents needed for the TFICF field, triggering the bug
(because then we had `it` ALWAYS equal to 1.0).

In the new API, while we cannot prevent the bug at the type level we can
easily do an audit by grepping for `countRows`, making sure we have exactly one instance,
i.e. inside `mkOpaCountQuery`.