CLN: Revert "Return Python integers" (not needed after pandas-dev#20989)

This reverts commit 8e3d4d0.

Author: toobaz

pandas/_libs/index.pyx

@@ -195,7 +195,7 @@ cdef class IndexEngine:
         if count > 1:
             return indexer
         if count == 1:
-            return int(found[0])
+            return found[0]
 
         raise KeyError(val)
 

pandas/_libs/index_class_helper.pxi.in

@@ -74,7 +74,7 @@ cdef class {{name}}Engine(IndexEngine):
         if count > 1:
             return indexer
         if count == 1:
-            return int(found[0])
+            return found[0]
 
         raise KeyError(val)