Remove use of string rather than straddle OTP version

string functions were used in unit tetss only, and were replaceable with io_lib:format

src/leveled_util.erl

@@ -16,18 +16,6 @@
             integer_time/1,
             magic_hash/1]).
 
--export([string_right/3,
-         string_str/2]).
-
--ifdef(OTP_RELEASE).
-
--if(?OTP_RELEASE >= 21).
--else.
--define(LEGACY_OTP, true).
--endif.
-
--endif.  % (OTP_RELEASE)
-
 
 -spec generate_uuid() -> list().
 %% @doc
@@ -76,47 +64,6 @@ hash1(H, <<B:8/integer, Rest/bytes>>) ->
     H2 = H1 bxor B,
     hash1(H2, Rest).
 
-%% A number of string functions have become deprecated in OTP 21
-%%
--ifdef(LEGACY_OTP).
-
-string_right(String, Len, Char) ->
-    string:right(String, Len, Char).
-
-string_str(S, Sub) ->
-    string:str(S, Sub).
-
--else.
-
-string_right(String, Len, Char) when is_list(String), is_integer(Char) ->
-    Slen = length(String),
-    if
-	Slen > Len -> lists:nthtail(Slen-Len, String);
-	Slen < Len -> chars(Char, Len-Slen, String);
-	Slen =:= Len -> String
-    end.
-
-chars(C, N, Tail) when N > 0 ->
-    chars(C, N-1, [C|Tail]);
-chars(C, 0, Tail) when is_integer(C) ->
-    Tail.
-
-
-string_str(S, Sub) when is_list(Sub) -> str(S, Sub, 1).
-
-str([C|S], [C|Sub], I) ->
-    case l_prefix(Sub, S) of
-        true -> I;
-        false -> str(S, [C|Sub], I+1)
-    end;
-str([_|S], Sub, I) -> str(S, Sub, I+1);
-str([], _Sub, _I) -> 0.
-
-l_prefix([C|Pre], [C|String]) -> l_prefix(Pre, String);
-l_prefix([], String) when is_list(String) -> true;
-l_prefix(Pre, String) when is_list(Pre), is_list(String) -> false.
-
--endif.
 
 %%%============================================================================
 %%% Test