Prevent empty <ul> from being rendered in profile.html

[DanielSwain]

Description

An empty <ul> was being rendered when backup_phones == None. Whitespace was also being rendered between the <ul></ul>.

Motivation and Context

The rendered element causes extra space to appear in the DOM at http://127.0.0.1:8000/account/two_factor/ before the "Add Phone Number" button when no backup phones have been registered.

How Has This Been Tested?

Tested locally at http://127.0.0.1:8000/account/two_factor/. An empty <ul></ul> is no longer rendered when navigating to this url prior to adding any backup phone numbers.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e9dba63) 95.52% compared to head (87f9680) 95.52%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #695   +/-   ##
=======================================
  Coverage   95.52%   95.52%           
=======================================
  Files          78       78           
  Lines        3354     3354           
  Branches      377      377           
=======================================
  Hits         3204     3204           
  Misses        119      119           
  Partials       31       31           

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[claudep]

Thanks, looks good!