sql: add labels to all stmt type metrics

This commit audits all "started" and "executed" query metrics to add
`sql.started.count` and `sql.count` labels, respectively, so that
rolling up across all stmt types would equal to what is tracked via
`sql.query.started.count` and `sql.query.count`, respectively.

Note that we have separate `sql.crud_query.*` metrics for CRUD queries,
so if a customer only wants to include 4 types of stmts, then they'll
have to explicitly specify the stmt types when aggregating.

Release note: None

Author: yuzefovich