drop sort parameter for autocomplete

[eviljeff]

we should always use relevance sort for addon autocomplete results

[ioanarusiczki]

@eviljeff
My test results:
I tested with a couple of queries (I tried with those that would return a smaller number of results to see better if their order is different or not)
https://addons-dev.allizom.org/api/v5/addons/autocomplete/?q=iridium
https://addons-dev.allizom.org/api/v5/addons/autocomplete/?q=BDMP

Adding for -dev a sort parameter such as
https://addons-dev.allizom.org/api/v5/addons/autocomplete/?q=iridium&sort=hotness or any other (including random which previously was not available without recommended) will return the list of results in the same order as before (when I only used a q) which means that the relevance is always kept and the rest of the parameters are being ignored.

dev - same order by relevance

stage - different order depending on the sort type

Let me know if there's anything else I should check on.
Thanks!