changed default show_legend = True for hv.Path elements

[ea42gh]

No description provided.

[ea42gh]

Addresses issue #2601

[philippjfr]

Sorry I didn't get around to review this. The problem here is that in many cases you are plotting a lot of paths which might be colored by different values and you do not want to generate a legend for this case by default. This is the original reason this was disabled by default, so simply setting it to true is not something I'm okay with merging. I don't currently have an alternative suggestion though.

[jbednar]

Should it respect the legend_limit based on the length of the path, as Overlays do?

[ea42gh]

We had gone through a discussion of this in the past:
#2601
The conclusion there appears to have been that legends only appear if explicitley requested
with a label='...' argument. Caveat Emptor

I also found
#3190
which I had totally forgotten about...

I seem to get bitten by this about once a year:
https://discourse.holoviz.org/t/paths-do-not-display-legends-by-default/2252

As an alternative, might an argument "label='...'" without setting show_legend=True trigger a warning?