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/

pkgs/misc/screensavers/i3lock-pixeled/default.nix

@@ -16,7 +16,6 @@ stdenv.mkDerivation rec {
     playerctl
   ];
 
-  buildPhases = [ "unpackPhase" "patchPhase" "installPhase" ];
   makeFlags = [
     "PREFIX=$(out)/bin"
   ];

pkgs/servers/tt-rss/default.nix

@@ -10,8 +10,6 @@ stdenv.mkDerivation rec {
     sha256 = "07ng21n4pva56cxnxkzd6vzs381zn67psqpm51ym5wnl644jqh08";
   };
 
-  buildPhases = ["unpackPhase" "installPhase"];
-
   installPhase = ''
     mkdir $out
     cp -ra * $out/

pkgs/servers/web-apps/selfoss/default.nix

@@ -11,8 +11,6 @@ stdenv.mkDerivation rec {
     sha256 = "00vrpw7sb95x6lwpaxrlzxyj98k98xblqcrjr236ykv0ha97xv30";
   };
 
-  buildPhases = ["unpackPhase" "installPhase"];
-
   installPhase = ''
     mkdir $out
     cp -ra * $out/

pkgs/shells/lambda-mod-zsh-theme/default.nix

@@ -10,8 +10,6 @@ stdenv.mkDerivation {
     rev = "61c373c8aa5556d51522290b82ad44e7166bced1";
   };
 
-  buildPhases = [ "unpackPhase" "installPhase" ];
-
   installPhase = ''
     mkdir -p $out/share/themes
     cp lambda-mod.zsh-theme $out/share/themes

pkgs/shells/zsh-autosuggestions/default.nix

@@ -15,8 +15,6 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ zsh ];
 
-  buildPhases = [ "unpackPhase" "installPhase" ];
-
   installPhase = ''
     install -D zsh-autosuggestions.zsh \
       $out/share/zsh-autosuggestions/zsh-autosuggestions.zsh