Disable CONCATENATE_SCRIPTS by default

[kadamwhite]

In Altis, we have HTTP2 and a strong caching layer. We've observed issues on several projects where the wp admin script concatenation caused 502 or 504 errors, sometimes dramatically slowing down the entire admin load times, because WordPress was trying to concatenate admin scripts using load-scripts.php

Setting CONCATENATE_SCRIPTS to false resolved this issue, and since we don't require the server side concatenation at all on Altis, should we set this to false by default in the CMS module config?

[rmccue]

I think there's a ticket in Trac about doing similar in core, but unable to find it now. Last I recalled there were some potential compatibility issues but cannot remember what they were (or why they existed)