[Lens] Axis controls look too much like sorting controls

[ghudgins]

Describe the feature:
For these icons in Lens, consider changing the arrow from <-> to just ->. Consider other ways to solve this as well, this is just a suggestion

Describe a specific use case for the feature:
We have some informal usability feedback that this icon can look like sort control instead of axis controls.

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[ghudgins]

+1

hey would actually like to set the Y-Axis label as "Metric X (in seconds, with millisecond precision)", but I can't find a way to do that in Lens

[markov00]

cc @MichaelMarcialis what do you think? is it possible to clean this a bit?
Is pretty straight forward and can definitely improve the readability of these buttons

[MichaelMarcialis]

@markov00: Absolutely. I've disliked these icons for a while and would love to take a stab at improving them. I'll add it to my list of Lens priorities, following the items @teresaalvarezsoler has prioritized.