Setting CDF plot reorders the Pf vector for HVDC permanently

[Carlos-Alegre]

Describe the bug
After toggling the CDF tickbox for plotting results of a DCOPF with time series, the list of Pf is reorder to generate the plot. Unticking the boxes undos the reorder for most vectors, but the Pf for HVDC remains unchanged, with the CDF order. This results in wrong information in the plots and the results table.

To Reproduce
Steps to reproduce the behavior:

1. Run a DCOPF with time series
2. Tick the CDF plotting option
3. Untick again
4. The list of Pf remains ordered for a CDF plot instead of going back to its time series results.

[SanPen]

probably fixed by creating data copies in ResultsTable.convert_to_cdf()