[CI] Remove "Clean up provisioning profile" step from iOS workflows

Summary:
Removes the "Clean up provisioning profile" step from GH Actions iOS workflows since it's unnecessary.

We're no longer passing in any provisioning profiles, so there's nothing to delete

Test Plan: Made sure it was fine to remove this step in a fork of repo

Reviewers: tomek, varun, marcin, rohan, ginsu, ashoat

Reviewed By: ashoat

Subscribers: ashoat, abosh

Differential Revision: https://phab.comm.dev/D5552