Automation-controller: automation-controller-container: automation-controller/awx: bulk job launch checks instance_groups at read level instead of use level, allowing execution-placement authorization bypass

A flaw was found in Ansible Automation Platform's automation-controller (AWX).
The Bulk Job Launch API (POST /api/v2/bulk/job_launch/) authorizes the
requested instance_groups with only a read-level permission check, whereas the
standard single-job launch path requires use-level permission on the same
field. A principal that holds read (but not use) permission on an instance
group -- for example the built-in read-only System Auditor role -- together
with execute permission on a job template can launch bulk jobs onto instance
groups they are not authorized to use, bypassing execution-placement
isolation.