If backticks are used in db/table names, QC stores fullnames explicitly

An example:

2022-11-08 08:19:52   warning: (7) [qc_sqlite] The table 'information_schema.global_variables' is not found in the canonical statement 'DESCRIBE `information_schema`.`global_variables`' created from the statement 'DESCRIBE `information_schema`.`global_variables`'.

If backticks are used, then the full-name, e.g. information_schema.global_variables, will not be found in the canonicalized statement, which leads some wasted (not leaked) memory and to a warning being logged in debug mode.

The QC API should be changed so that this problem disappears entirelly.