Track the number of performed monitoring intervals

Tracking how many times the monitor has performed its monitoring allows
the test framework to consistently wait for an event instead of waiting
for a hard-coded time period. The MaxCtrl `api get` command can be used to
easily extract the numeric value.

server/core/config.cc

@@ -148,6 +148,7 @@ const char CN_STRIP_DB_ESC[]                  = "strip_db_esc";
 const char CN_SUBSTITUTE_VARIABLES[]          = "substitute_variables";
 const char CN_THREADS[]                       = "threads";
 const char CN_THREAD_STACK_SIZE[]             = "thread_stack_size";
+const char CN_TICKS[]                         = "ticks";
 const char CN_TYPE[]                          = "type";
 const char CN_UNIX[]                          = "unix";
 const char CN_USER[]                          = "user";