Remove ColMap (#19544)

Now that gorp is gone, this is no longer
required.

```release-note
NONE
```

store/sqlstore/system_store.go

@@ -23,15 +23,7 @@ type SqlSystemStore struct {
 }
 
 func newSqlSystemStore(sqlStore *SqlStore) store.SystemStore {
-	s := &SqlSystemStore{sqlStore}
-
-	for _, db := range sqlStore.GetAllConns() {
-		table := db.AddTableWithName(model.System{}, "Systems").SetKeys(false, "Name")
-		table.ColMap("Name").SetMaxSize(64)
-		table.ColMap("Value").SetMaxSize(1024)
-	}
-
-	return s
+	return &SqlSystemStore{sqlStore}
 }
 
 func (s SqlSystemStore) Save(system *model.System) error {