[beaker-tests-sanity] remove the complicated sed
    
    I must admit that I don't understand the reason why the sed is here.
    We wan't to take a part of JSON data (which should be valid JSON by
    themselves) from `jq` command, then store it to a file. Then other tests
    are getting the data and processing them through `jq` again. I see no
    point in modifying them manually with sed.
    
    Moreover, the sed breaks the JSON format and unables `jq` to read the
    data. It generates output like this
    
        pypi_package_name": "motionpaint,
    
    missing the opening quote for key and ending quote for value.