Update active section selector for ggrc-core commit e7eadac2.

An `li` tag instead of a `section` tag gets labeled as active due to [this commit](https://github.com/reciprocity/ggrc-core/commit/e7eadac2) in ggrc-core, requiring an update of the `section_active` selector that the test uses to determine whether the right section has been set to active.