Copy update to terms on step 1 of free, trial, and invite registration flows

Summary

There have been a few copy updates and changes to step 1 of our registration flows. Currently the terms combine marketing opt-in with "clicking continue or registering through a third party" language. This is not necessary and can be simplified for all 3 registration flows (free, trial, invite)

Update

As confirmed with @emccrann, we can simplify the copy of the 'opt-in' checkbox to:

I agree that GitLab may contact me by email and telephone about its product, services and events.

Implementation details

exact place in code to edit to modify