treewide: get rid of invalid buildPhases argument

I don't know where this comes from (I accidentally did that as well
once), but some derivations seem to use `buildPhases` rather than
`phases` in their derivations.

This kills all improper usages as the lack of a `phases` argument
didn't break the build, so this can be safely removed.

nixos/modules/services/search/solr.nix

@@ -15,8 +15,6 @@ let
       sha256 = "01mzvh53wrs1p2ym765jwd00gl6kn8f9k3nhdrnhdqr8dhimfb2p";
     };
 
-    buildPhases = [ "unpackPhase" "installPhase" ];
-
     installPhase = ''
       mkdir -p $out/lib
       cp common/lib/*.jar $out/lib/