REF: make remaining offset classes cdef (#34419)

Author: jbrockmendel

pandas/_libs/tslibs/offsets.pyx

@@ -3337,7 +3337,7 @@ cdef class CustomBusinessDay(BusinessDay):
         return np.is_busday(day64, busdaycal=self.calendar)
 
 
-class CustomBusinessHour(BusinessHour):
+cdef class CustomBusinessHour(BusinessHour):
     """
     DateOffset subclass representing possibly n custom business days.
     """
@@ -3379,7 +3379,7 @@ class CustomBusinessHour(BusinessHour):
         )
 
 
-class _CustomBusinessMonth(BusinessMixin, MonthOffset):
+cdef class _CustomBusinessMonth(BusinessMixin):
     """
     DateOffset subclass representing custom business month(s).
 
@@ -3406,9 +3406,6 @@ class _CustomBusinessMonth(BusinessMixin, MonthOffset):
         ["n", "normalize", "weekmask", "holidays", "calendar", "offset"]
     )
 
-    is_on_offset = BaseOffset.is_on_offset  # override MonthOffset method
-    apply_index = BaseOffset.apply_index  # override MonthOffset method
-
     def __init__(
         self,
         n=1,
@@ -3480,11 +3477,11 @@ class _CustomBusinessMonth(BusinessMixin, MonthOffset):
         return result
 
 
-class CustomBusinessMonthEnd(_CustomBusinessMonth):
+cdef class CustomBusinessMonthEnd(_CustomBusinessMonth):
     _prefix = "CBM"
 
 
-class CustomBusinessMonthBegin(_CustomBusinessMonth):
+cdef class CustomBusinessMonthBegin(_CustomBusinessMonth):
     _prefix = "CBMS"