RANSACRegressor does not pass weights to the used estimator during the training of the final model.

Sample weights to RANSAC have been requested by #5871 and #6113, and implemented in #6140, but the weights of the final inlier sample are not used during the training of the final model.

The issue only causes crashes when using a custom estimator which always requires the sample_weight parameter to be passed to it, as is the case in the training of the final estimator with the current implementation.