[Lens] Drilldowns to discover are not shown in dashboard

[wylieconlon]

The "Explore underlying data" option that other visualizations have in dashboard appear not to be registered for Lens visualizations. I don't know if it was ever available, but it's notably missing on master.

cc @streamich @Dosant not sure if this was ever supported?

[elasticmachine]

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

[Dosant]

@wylieconlon, I took a quick look.

Explore underlying action is available for embeddables that report a single index pattern. This is known and user-facing documented limitation.

I think it worked before for simple lens visualizations (with a single index pattern), but I just reproduced that it is indeed doesn't work.

This is my test visualization:

And for some reason lens embeddable reports two identical index patterns:

embeddable.getOutput().indexPatterns 

Could it be a regression in lens embeddable on how index patterns reported in the embeddable output?

[wylieconlon]

@Dosant thanks for taking a look! This does look like a regression, I think it's caused by this PR which was merged to 7.10: #74523