Where an enactment, other than this part, authorizes or requires a local public entity to insure against its liability or the liability of its employees:
(a) The authority provided by this part to insure does not affect such other enactment.
(b) Such other enactment does not limit or restrict the authority to insure under this part; but, except to the extent authorized by Section 1251 of the Education Code, nothing in this part permits a school district to self-insure in any case where the school district is required to insure.