Make textual inversion script work again (#4978)

## What type of PR is this? (check all applicable)

- [ ] Refactor
- [ ] Feature
- [X] Bug Fix
- [ ] Optimization
- [ ] Documentation Update
- [ ] Community Node Submission


## Have you discussed this change with the InvokeAI team?
- [X] Yes
- [ ] No, because:

      
## Have you updated all relevant documentation?
- [X] Yes
- [ ] No


## Description

Fix textual inversion training script crash caused by reorg of services.

## Related Tickets & Documents

- closes #4975

<!--
For pull requests that relate or close an issue, please include them
below. 

For example having the text: "closes #1234" would connect the current
pull
request to issue 1234.  And when we merge the pull request, Github will
automatically close the issue.
-->

- Related Issue #
- Closes #

## QA Instructions, Screenshots, Recordings

<!-- 
Please provide steps on how to test changes, any hardware or 
software specifications as well as any other pertinent information. 
-->

## Added/updated tests?

- [ ] Yes
- [ ] No : _please replace this line with details on why tests
      have not been included_

## [optional] Are there any post deployment tasks we need to perform?

invokeai/app/services/model_manager/__init__.py

@@ -0,0 +1 @@
+from .model_manager_default import ModelManagerService

invokeai/backend/training/textual_inversion_training.py

@@ -41,7 +41,7 @@ from transformers import CLIPTextModel, CLIPTokenizer
 
 # invokeai stuff
 from invokeai.app.services.config import InvokeAIAppConfig, PagingArgumentParser
-from invokeai.app.services.model_manager_service import ModelManagerService
+from invokeai.app.services.model_manager import ModelManagerService
 from invokeai.backend.model_management.models import SubModelType
 
 if version.parse(version.parse(PIL.__version__).base_version) >= version.parse("9.1.0"):