Allow border of legend not change according to the type of line in the graph

### Feature Proposal

Take a look at the image below. Some legends have the border line dashed/dotted just because the line in the graph is dashed/dotted. That's nice, but it would be good to be able to disable this because sometimes the legends get really weird especially when some dataset lines are thicker than others, that makes the border line of the legend also thicker and when you have many legends, they get completely confused with each one having different border line thickness. This problem also happens when I hover a line in the graph and it gets thicker, this will make the border line of the legend to get thicker which misaligns the legends. It would be nice to disable this in order to the legends have fixed line thickness and be completely solid instead of using dashed/dotted.


### Possible Implementation

_No response_