Remove (again) our deprecated hashing methods

[chriswk]

Describe the feature request

To avoid users complaining about not seeing full/even distribution we should remove the methods that were added in 9.2.0 for simplifying the upgrade path from 8.x to 9.x. Ideally in 10.x but at the latest at 11.x

Background

In #232 an active user complained that the upgrade from 8.3.1 to 9.x broke the way they worked, so in 9.2.0 we added methods allowing to use the old seed for the hashing of the variants.

Solution suggestions

As the title says, we should remove the deprecated methods as soon as possible, to avoid having more users falling down the rabbit hole of having a 10% allocation getting the feature and then not seeing a 50/50 split between two variants of 50% / 50% weight.