Improve specs for integration_settings_form_spec.js

The following discussion from !71518 (merged) should be addressed:

• @aturinske started a discussion: (+2 comments)

  question (non-blocking): I am surprised that there are not more tests that need to be updated that are similar to this one; like in spec/frontend/integrations/integration_settings_form_spec.js I would have thought there were some tests like emits "validateFrom" to the eventHub when.... I do not know this part of the code, so maybe they aren't useful (or maybe in general they aren't useful? 🤷 ), but maybe it is worth a follow-up to add some more tests? WDYT?