refactor(path): remove dead code (#7180)

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

otherlibs/stdune/src/path.ml

@@ -1129,16 +1129,6 @@ let extend_basename t ~suffix =
   | In_build_dir t -> in_build_dir (Local.extend_basename t ~suffix)
   | External t -> external_ (External.extend_basename t ~suffix)
 
-let insert_after_build_dir_exn =
-  let error a b =
-    Code_error.raise "Path.insert_after_build_dir_exn"
-      [ ("path", to_dyn a); ("insert", String b) ]
-  in
-  fun a b ->
-    match a with
-    | In_build_dir a -> in_build_dir (Local.append (Local.of_string b) a)
-    | In_source_tree _ | External _ -> error a b
-
 let clear_dir dir = Fpath.clear_dir (to_string dir)
 
 let rm_rf ?(allow_external = false) t =

otherlibs/stdune/src/path.mli

@@ -352,8 +352,6 @@ val is_strict_descendant_of_build_dir : t -> bool
 (** Split after the first component if [t] is local *)
 val split_first_component : t -> (Filename.t * t) option
 
-val insert_after_build_dir_exn : t -> string -> t
-
 val exists : t -> bool
 
 val readdir_unsorted :

otherlibs/stdune/test/path_tests.ml

@@ -35,9 +35,6 @@ let reach_for_running p ~from =
 
 let relative p s = Path.to_dyn (Path.relative p s) |> print_dyn
 
-let insert_after_build_dir_exn p s =
-  Path.insert_after_build_dir_exn p s |> Path.to_dyn |> print_dyn
-
 let append_source x y = Path.append_source x y |> Path.to_dyn |> print_dyn
 
 let drop_build_context p =
@@ -292,26 +289,6 @@ let%expect_test _ =
 false
 |}]
 
-let%expect_test _ =
-  insert_after_build_dir_exn Path.root "foobar";
-  [%expect.unreachable]
-  [@@expect.uncaught_exn
-    {|
-  ( "(\"Path.insert_after_build_dir_exn\",\
-   \n{ path = In_source_tree \".\"; insert = \"foobar\" })") |}]
-
-let%expect_test _ =
-  insert_after_build_dir_exn Path.build_dir "foobar";
-  [%expect {|
-In_build_dir "foobar"
-|}]
-
-let%expect_test _ =
-  insert_after_build_dir_exn (Path.relative Path.build_dir "qux") "foobar";
-  [%expect {|
-In_build_dir "foobar/qux"
-|}]
-
 let%expect_test _ =
   append_source Path.build_dir (Path.Source.relative Path.Source.root "foo");
   [%expect {|
@@ -423,12 +400,6 @@ let%expect_test _ =
 "c/d"
 |}]
 
-let%expect_test _ =
-  local_part (Path.insert_after_build_dir_exn Path.build_dir "c/d");
-  [%expect {|
-"c/d"
-|}]
-
 let%expect_test _ =
   local_part (r "c/d");
   [%expect {|