Properly default pretend_min_part_hours_passed

The pretend_min_part_hours_passed value inside the swift_rings.py was
not typed correctly, and so was being run by default.

Change-Id: Ib7686789fbd948291633b7fabc8961bad2810114

templates/swift_rings.py.j2

@@ -258,7 +258,7 @@ if __name__ == "__main__":
         help="Reset the clock on the last time a rebalance happened.",
         dest="reset_mph_clock",
         action="store_true",
-        default='False'
+        default=False
     )
 
     options, _args = parser.parse_args(sys.argv[1:])