Turn data collection notice into a warning

[willdurand]

Refs mozilla/addons#15890

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.78%. Comparing base (feaf47c) to head (9498057).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5817   +/-   ##
=======================================
  Coverage   98.78%   98.78%           
=======================================
  Files          51       51           
  Lines        2888     2888           
  Branches      886      886           
=======================================
  Hits         2853     2853           
  Misses         35       35           

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[rpl]

lgtm