Update best_practices.md

Remove duplicate list item in "General Guidelines" Section.

doc/development/testing_guide/best_practices.md

@@ -26,7 +26,6 @@ Here are some things to keep in mind regarding test performance:
 - Use `.method` to describe class methods and `#method` to describe instance
   methods.
 - Use `context` to test branching logic.
-- Don't assert against the absolute value of a sequence-generated attribute (see [Gotchas](../gotchas.md#dont-assert-against-the-absolute-value-of-a-sequence-generated-attribute)).
 - Try to match the ordering of tests to the ordering within the class.
 - Try to follow the [Four-Phase Test][four-phase-test] pattern, using newlines
   to separate phases.