Techdebt: Simplify GreenGrass responses (#7633)

Author: bblommers

moto/core/responses.py

@@ -491,7 +491,7 @@ def uri_to_regexp(self, uri: str) -> str:
 
         def _convert(elem: str, is_last: bool) -> str:
             if not re.match("^{.*}$", elem):
-                return elem
+                return elem.replace("$", r"\$")
             name = (
                 elem.replace("{", "")
                 .replace("}", "")