Except as provided in Sections 15304 to 15307, inclusive, if the trust instrument provides that the trustee shall pay income or principal or both for the education or support of a beneficiary, the beneficiary’s interest in income or principal or both under the trust, to the extent the income or principal or both is necessary for the education or support of the beneficiary, may not be transferred and is not subject to the enforcement of a money judgment until paid to the beneficiary.