Description of problem: On 24 core/48 thread servers, with a 3 node HA deployment, scaling to 20+ compute nodes resulted in a failed tenant instance boot because the mysql connection limit was reached.  Even idle, the connection count was sitting around 900.


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


How reproducible: On any hardware with a lot of cores.


Steps to Reproduce:
1. Deploy with OSP director on hardware with 48 or more threads available.
2. Attempt to do anything significant on the overcloud.
3.

Actual results: 500 errors from services due to no available mysql connections.


Expected results: Working overcloud


Additional info: This is likely because we scale the api processes based on number of cores, and 48 api processes across three controllers adds up to a lot of mysql connections.  We need to increase the default, or make it configurable.