Remove unnecessary atomic decorators from tasks

The `atomic` decorator isn't actually needed on these task functions.
Any parts of the tasks that need to be atomic are already marked as
such inside the functions that the tasks call.

dandiapi/api/tasks/__init__.py

@@ -1,6 +1,5 @@
 from celery import shared_task
 from celery.utils.log import get_task_logger
-from django.db.transaction import atomic
 
 from dandiapi.api.doi import delete_doi
 from dandiapi.api.manifests import (
@@ -33,7 +32,6 @@ def calculate_sha256(blob_id: str) -> None:
 
 
 @shared_task(soft_time_limit=180)
-@atomic
 def write_manifest_files(version_id: int) -> None:
     version: Version = Version.objects.get(id=version_id)
     logger.info('Writing manifests for version %s:%s', version.dandiset.identifier, version.version)
@@ -46,7 +44,6 @@ def write_manifest_files(version_id: int) -> None:
 
 
 @shared_task(soft_time_limit=10)
-@atomic
 def validate_asset_metadata_task(asset_id: int) -> None:
     from dandiapi.api.services.metadata import validate_asset_metadata
 
@@ -56,7 +53,6 @@ def validate_asset_metadata_task(asset_id: int) -> None:
 
 
 @shared_task(soft_time_limit=30)
-@atomic
 def validate_version_metadata_task(version_id: int) -> None:
     from dandiapi.api.services.metadata import validate_version_metadata
 
@@ -78,7 +74,6 @@ def unembargo_dandiset_task(dandiset_id: int):
 
 
 @shared_task
-@atomic
 def publish_dandiset_task(dandiset_id: int):
     from dandiapi.api.services.publish import _publish_dandiset