Mumford coordinates are not always reduced for even degree model

[GiacomoPope]

Steps To Reproduce

When summing divisors for even degree models, the cantor reduction sometimes does not finish the reduction process. This seems to be due to a TODO left in the code.

sage: F = GF(163)
sage: R.<x> = PolynomialRing(F)
sage: f = x^6 + x^2 + 1
sage: H = HyperellipticCurve(f)
sage: J = H.jacobian()
sage: Ps = H.points()
sage: Ds = [J(P) for P in Ps]
sage: sum(choice(Ds) for _ in range(7))
Returning ambiguous form of degree genus+1.
Returning ambiguous form of degree genus+1.
Returning ambiguous form of degree genus+1.
(x^3 + 11*x^2 + 104*x + 136, y + 95*x^2 + 144*x + 156)

Expected Behavior

The mumford polynomials are reduced.

Actual Behavior

The mumford polynomials are not reduced

Additional Information

No response

Environment

- **OS**: MacOS
- **Sage Version**: SageMath 10.2

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[GiacomoPope]

Combined into the issue #37109 as the fix is identical.