treewide: clean up obsolete version checks

These checks are all redundant with the check for Nix ≥2.2 in
default.nix.

pkgs/build-support/fetchipfs/default.nix

···
 , preferLocalBuild ? true
 }:
 
-assert sha512 != "" -> builtins.compareVersions "1.11" builtins.nixVersion <= 0;
-
 let
 
   hasHash = (outputHash != "" && outputHashAlgo != "")

pkgs/build-support/fetchurl/default.nix

···
 , nativeBuildInputs ? [ ]
 }:
 
-assert sha512 != "" -> builtins.compareVersions "1.11" builtins.nixVersion <= 0;
-
 let
   urls_ =
     if urls != [] && url == "" then

pkgs/build-support/nix-gitignore/default.nix

···
 let
   debug = a: trace a a;
   last = l: elemAt l ((length l) - 1);
-
-  throwIfOldNix = let required = "2.0"; in
-    if compareVersions nixVersion required == -1
-    then throw "nix (v${nixVersion} =< v${required}) is too old for nix-gitignore"
-    else true;
 in rec {
   # [["good/relative/source/file" true] ["bad.tmpfile" false]] -> root -> path
   filterPattern = patterns: root:
···
 
   # string -> [[regex bool]]
   gitignoreToPatterns = gitignore:
-    assert throwIfOldNix;
     let
       # ignore -> bool
       isComment = i: (match "^(#.*|$)" i) != null;

pkgs/top-level/all-packages.nix

···
 
   nix-repl = throw (
     "nix-repl has been removed because it's not maintained anymore, " +
-    (lib.optionalString (!lib.versionAtLeast "2" (lib.versions.major builtins.nixVersion)) "ugrade your Nix installation to a newer version and ") +
     "use `nix repl` instead. Also see https://github.com/NixOS/nixpkgs/pull/44903"
   );