Migrate Channelstore categories to sqlx (#19506)

Remove db:"-" tags from model.Channel as well.

```release-note
NONE
```

store/storetest/mocks/dbSelecter.go

@@ -12,27 +12,18 @@ type dbSelecter struct {
 }
 
 // Select provides a mock function with given fields: i, query, args
-func (_m *dbSelecter) Select(i interface{}, query string, args ...interface{}) ([]interface{}, error) {
+func (_m *dbSelecter) Select(i interface{}, query string, args ...interface{}) error {
 	var _ca []interface{}
 	_ca = append(_ca, i, query)
 	_ca = append(_ca, args...)
 	ret := _m.Called(_ca...)
 
-	var r0 []interface{}
-	if rf, ok := ret.Get(0).(func(interface{}, string, ...interface{}) []interface{}); ok {
+	var r0 error
+	if rf, ok := ret.Get(0).(func(interface{}, string, ...interface{}) error); ok {
 		r0 = rf(i, query, args...)
 	} else {
-		if ret.Get(0) != nil {
-			r0 = ret.Get(0).([]interface{})
-		}
+		r0 = ret.Error(0)
 	}
 
-	var r1 error
-	if rf, ok := ret.Get(1).(func(interface{}, string, ...interface{}) error); ok {
-		r1 = rf(i, query, args...)
-	} else {
-		r1 = ret.Error(1)
-	}
-
-	return r0, r1
+	return r0
 }