temp: disable price edits if course has a published run

[DawoudSheraz]

PROD-4264

Description

• Disable price edit if a course has published runs (this is temporary and will be removed)
• Only display sitewide banner if there is some content to display. The default banner without any content was always displaying and did not look alright.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.86%. Comparing base (4a6684f) to head (160ec06).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #994      +/-   ##
==========================================
- Coverage   67.90%   67.86%   -0.05%     
==========================================
  Files         129      129              
  Lines        3247     3249       +2     
  Branches      941      943       +2     
==========================================
  Hits         2205     2205              
+ Misses        997      996       -1     
- Partials       45       48       +3     

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