Fix messy Base Browser CI commits
In this MR (!1297 (merged)) I refactored the CI code and extracted part of the code in lint.yml to mixins.yml. However I did that on a tor-browser commit, even though part of that code is in the base-browser commit.
In this MR (!1297 (merged)) I refactored the CI code and extracted part of the code in lint.yml to mixins.yml. However I did that on a tor-browser commit, even though part of that code is in the base-browser commit.