Port TG Tooling Fix in MapMerge (#5527)

# About the pull request

This PR ports tgstation/tgstation#77283 and
corrects an incorrect default value in update paths.

# Explain why it's good for the game
Fixes an edge case with map merge tools.

# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
No player facing changes.

tools/UpdatePaths/__main__.py

@@ -27,7 +27,7 @@
     property = @UNSET - will apply the rule only if the property is not mapedited
 """
 
-default_map_directory = "../maps"
+default_map_directory = "../../maps"
 replacement_re = re.compile(r'\s*(?P<path>[^{]*)\s*(\{(?P<props>.*)\})?')
 
 #urgent todo: replace with actual parser, this is slow as janitor in crit

tools/mapmerge2/dmm.py

@@ -95,7 +95,7 @@ def _presave_checks(self):
         # last-second handling of bogus keys to help prevent and fix broken maps
         self._ensure_free_keys(0)
         max_key = max_key_for(self.key_length)
-        bad_keys = {key: 0 for key in self.dictionary.keys() if key > max_key}
+        bad_keys = {key: 0 for key in self.dictionary.keys() if key >= max_key}
         if bad_keys:
             print(f"Warning: fixing {len(bad_keys)} overflowing keys")
             for k in bad_keys: