[php-src] Issue #8345: ODBC's heuristic for guessing if DSN or connection string could be better

Issue: https://github.com/php/php-src/issues/8345 Comment Author: NattyNarwhal Right, it could be called either. I do agree changing this in older releases would be a surprise change in behaviour. A lot of the motivation for the ODBC cleanups I'm trying to do is having to explain the difference in behaviour (the abstraction leak) to our users at work. There, it does seem like a bug from that perspective (i.e. why does one work but not the other?), so that's why I leaned towards calling it one here.