Description of problem:
When using the API to request a bulk refresh of alternate content sources, invalid ids will be discarded if there is a single valid ACS id in the query.

Version-Release number of selected component (if applicable):
n/a

How reproducible:
Always

Steps to Reproduce:
1. Create a Sat instance with an alternate content source, note the id.
2. Start a bulk refresh using the API, including the valid id along with several bogus id's:
`curl --request POST --user admin:changeme -H "Content-type: application/json" <host>/katello/api/alternate_content_sources/bulk/refresh?ids=<valid>,1001,1002,1003`

Actual results:
JSON output informing the user that the valid id alone has been refreshed

Expected results:
An error indicating invalid parameters

Additional info:
n/a