Fixes InstanceConfig model generation when validators functions are defined in spec.yaml (DataDog#21409)

* Fix additional field validators package in model generation

* Add changelog

Author: eric-weaver

datadog_checks_dev/changelog.d/21409.fixed

@@ -0,0 +1 @@
+Fixes InstanceConfig model generation when validators functions are defined in spec.yaml

datadog_checks_dev/datadog_checks/dev/tooling/configuration/consumers/model/model_file.py

@@ -162,7 +162,7 @@ def _define_validator_functions(model_id, validator_data, need_defaults):
         model_file_lines.append('')
         model_file_lines.append(f'            if info.field_name == {option_name!r}:')
         for import_path in import_paths:
-            model_file_lines.append(f'                value = validation.{import_path}(value, field=field)')
+            model_file_lines.append(f'                value = validators.{import_path}(value, field=field)')
 
     if need_defaults:
         model_file_lines.append('        else:')

datadog_checks_dev/tests/tooling/configuration/consumers/model/test_common_validators.py

@@ -99,12 +99,12 @@ def _validate(cls, value, info):
                     value = getattr(validators, f'instance_{info.field_name}', identity)(value, field=field)
 
                     if info.field_name == 'foo':
-                        value = validation.pkg.subpkg2.validate2(value, field=field)
-                        value = validation.pkg.subpkg2.validate1(value, field=field)
+                        value = validators.pkg.subpkg2.validate2(value, field=field)
+                        value = validators.pkg.subpkg2.validate1(value, field=field)
 
                     if info.field_name == 'tags':
-                        value = validation.pkg.subpkg1.validate2(value, field=field)
-                        value = validation.pkg.subpkg1.validate1(value, field=field)
+                        value = validators.pkg.subpkg1.validate2(value, field=field)
+                        value = validators.pkg.subpkg1.validate1(value, field=field)
 
                 return validation.utils.make_immutable(value)