Fix ICP sample indices after initialization

[keenan-burnett]

Currently, we resample the filtered_samples_inds at each iteration of ICP:

https://github.com/utiasASRL/vtr3/blob/0dc3213b89c8acd65d10eb49084bbb71fd0c8d65/main/src/vtr_lidar/src/modules/odometry/odometry_icp_module.cpp#L281-L295

This essentially "moves" the minimum of the cost function at each iteration of ICP. If we fixed filtered_samples_inds after the initialization steps, it might allow ICP to converge faster.

Currently, it often takes 20-40 iterations of ICP to converge which seems like too much.