unit/introspection added among tests executed by default

tests/test_helper.tcl

@@ -34,6 +34,7 @@ set ::all_tests {
     unit/slowlog
     unit/scripting
     unit/maxmemory
+    unit/introspection
 }
 # Index to the next test to run in the ::all_tests list.
 set ::next_test 0