What does this implement/fix? Explain your changes.

Removes "mae", "mse", "least_squares", "squared_loss", "lad", "least_absolute_deviation" and "absolute_loss" from docstrings.

Since the errors were standardized in 1.0, maybe they can be removed from the documentation, leaving only the deprecation text.

If PR #21306 is accepted, that only fixes the docstring in RandomForestRegression, It would be natural to fix the other classes documentations.

According to v1.0 changelog;

|API| The option for using the squared error via loss and criterion parameters was made more consistent. The preferred way is by setting the value to "squared_error". Old option names are still valid, produce the same models, but are deprecated and will be removed in version 1.2. :pr:19310 by :user:Christian Lorentzen <lorentzenchr>.

• For :class:ensemble.ExtraTreesRegressor, criterion="mse" is deprecated, use "squared_error" instead which is now the default.
• For :class:ensemble.GradientBoostingRegressor, loss="ls" is deprecated, use "squared_error" instead which is now the default.
• For :class:ensemble.RandomForestRegressor, criterion="mse" is deprecated, use "squared_error" instead which is now the default.
• For :class:ensemble.HistGradientBoostingRegressor, loss="least_squares" is deprecated, use "squared_error" instead which is now the default.
• For :class:linear_model.RANSACRegressor, loss="squared_loss" is deprecated, use "squared_error" instead.
• For :class:linear_model.SGDRegressor, loss="squared_loss" is deprecated, use "squared_error" instead which is now the default.
• For :class:tree.DecisionTreeRegressor, criterion="mse" is deprecated, use "squared_error" instead which is now the default.
• For :class:tree.ExtraTreeRegressor, criterion="mse" is deprecated, use "squared_error" instead which is now the default.

|API| The option for using the absolute error via loss and criterion parameters was made more consistent. The preferred way is by setting the value to "absolute_error". Old option names are still valid, produce the same models, but are deprecated and will be removed in version 1.2. :pr:19733 by :user:Christian Lorentzen <lorentzenchr>.

• For :class:ensemble.ExtraTreesRegressor, criterion="mae" is deprecated, use "absolute_error" instead.
• For :class:ensemble.GradientBoostingRegressor, loss="lad" is deprecated, use "absolute_error" instead.
• For :class:ensemble.RandomForestRegressor, criterion="mae" is deprecated, use "absolute_error" instead.
• For :class:ensemble.HistGradientBoostingRegressor, loss="least_absolute_deviation" is deprecated, use "absolute_error" instead.
• For :class:linear_model.RANSACRegressor, loss="absolute_loss" is deprecated, use "absolute_error" instead which is now the default.
• For :class:tree.DecisionTreeRegressor, criterion="mae" is deprecated, use "absolute_error" instead.
  For :class:tree.ExtraTreeRegressor, criterion="mae" is deprecated, use "absolute_error" instead.

So this PR also checks the following classes: