[1.7.x] Fixed #22720 -- Migrations attempt to create _order twice.

Backport of 6cfa2fae39 from master
[1.7.x] Adding test to fix of duplicate _order fields (#22720)

Backport of bf9953cfb8 from master
[1.7.x] Simplified, very slightly, some code in the oracle backend

Backport of e79725cdf9 from master
[1.7.x] Fixed several typos in Django

Backport of 1dcc603eff from master
[1.7.x] Fixed a typo that Tim Graham noticed

Backport of d240b29c08 from master