add task decorator back to command

[shanbady]

What are the relevant tickets?

Closes https://github.com/mitodl/hq/issues/9290

note: the openapi diff error appears to be unrelated to these changes

Description (What does it do?)

This PR re-introduces a missing celery task decorator to the sync_topics task

How can this be tested?

1. checkout main
2. attempt to run python manage.py sync_topic_embeddings
3. see that it fails with an error
4. checkout this branch
5. restart celery and re-run the command - note that it passes

[github-actions]

OpenAPI Changes

Show/hide 7 changes: 7 error, 0 warning, 0 info

7 changes: 7 error, 0 warning, 0 info
error	[request-parameter-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API GET /api/v1/learning_resources_search/
		removed the enum value 'hybrid' from the 'query' request parameter 'search_mode'

error	[request-parameter-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API GET /api/v1/learning_resources_user_subscription/
		removed the enum value 'hybrid' from the 'query' request parameter 'search_mode'

error	[request-parameter-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API GET /api/v1/learning_resources_user_subscription/check/
		removed the enum value 'hybrid' from the 'query' request parameter 'search_mode'

error	[request-parameter-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API POST /api/v1/learning_resources_user_subscription/subscribe/
		removed the enum value 'hybrid' from the 'query' request parameter 'search_mode'

error	[request-property-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API POST /api/v1/learning_resources_user_subscription/subscribe/
		removed the enum value 'hybrid' of the request property 'search_mode/allOf[#/components/schemas/SearchModeEnum]/'

error	[request-property-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API POST /api/v1/learning_resources_user_subscription/subscribe/
		removed the enum value 'hybrid' of the request property 'search_mode/allOf[#/components/schemas/SearchModeEnum]/'

error	[request-property-enum-value-removed] at head/openapi/specs/v1.yaml	
	in API POST /api/v1/learning_resources_user_subscription/subscribe/
		removed the enum value 'hybrid' of the request property 'search_mode/allOf[#/components/schemas/SearchModeEnum]/'

Unexpected changes? Ensure your branch is up-to-date with main (consider rebasing).

[mbertrand]

👍