REGTESTS: stick-table: test the traffic counters of the stick counters

REGTESTS: stick-table: test the traffic counters of the stick counters

The connection, session, request, error, failure and byte counters of
the stick tables had no coverage, nor had the sc_*, sc0_*, src_* and
table_* families giving access to them, nor sc_key, sc_tracked,
sc_trackers, table_trackers, table_server_id, table_expire, table_idle,
in_table, table_avl and table_cnt.

A single client connection issues a normal request, a request denied
with a 403 and a request answered with a 500 by the server so that the
request, error and failure counters all move, and the three access
families are compared against each other at each step.

The values are grouped into a few headers because vtest only parses a
limited number of them.