Remove timestamp correction from `combine_echodata`

[leewujung]

@b-reyes had a great insight that the reason why we currently (up until v0.6.2) have detection and correction of reversed or duplicated timestamps (ping_time, time1, etc) in combine_echodata was because we have been using xarray's merge function to combine multiple EchoData objects.

With @b-reyes new implementation to efficiently distribute data combination directly leveraging dask/zarr functionalities, we don't actually have to have this check and can keep the original data in the combined EchoData object/associated zarr file. This is actually better because we want the EchoData object to be as lossless as possible from the original instrument file.

So, we can:

• remove this check from the combine_echodata function
• continue to provide this as part of the QC functions
  • this is because we will need the timestamps to be cleaned up for downstream processing, e.g., during calibration and adding lat/lon.

See #798 for bug fixes/improvements needed for the timestamp cleaning function.

[b-reyes]

@leewujung thank you for your description above.

In addition to the removal of the check from combine_echodata, we should also do the following:

• Remove ek60_reversed_ping_time_test_data and test_ping_time_reversal functions from test_echodata_combine
• Remove params corresponding to reversed times in test_combine_echodata and special exceptions for it
• Allow the run of param_id = "ek80_nb_diff_range_sample" in test_combine_echodata

[b-reyes]

PR #835 addressed this issue by removing the time correction in combine_echodata and moving useful functions to qc/api.py, closing.