Remove AssertArg and AssertState

These don't offer anything over plain Assert, and their usage had
already been declared obsolescent.

Author: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/20221009210148.GA900071@nathanxps13

src/backend/utils/misc/guc-file.l

@@ -179,7 +179,7 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 		}
 		else
 		{
-			AssertState(DataDir);
+			Assert(DataDir);
 			join_path_components(abs_path, DataDir, location);
 			canonicalize_path(abs_path);
 		}

src/backend/utils/misc/guc.c

@@ -6081,9 +6081,9 @@ ParseLongOption(const char *string, char **name, char **value)
 	size_t		equal_pos;
 	char	   *cp;
 
-	AssertArg(string);
-	AssertArg(name);
-	AssertArg(value);
+	Assert(string);
+	Assert(name);
+	Assert(value);
 
 	equal_pos = strcspn(string, "=");