Remove edit toggle in the segment editor since it's an extra click and unnecessary

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Discarded
• Affects Version/s: None
• Fix Version/s: Master
• Component/s: Segments Editor
• Labels:
  • 7.3-ce-ga1
  • tango_frontend
  • tango_test_not_needed
• Epic/Theme:
  • Segmentation
• Epic Link: tango-sp-segments-admin-usability

We made the edit toggle for when we had different contributors and the user needed to change which contributor to modify. Now that we don't have that interface, we should remove this and only use the view mode based on permissions.