Fix lower zorder traces behing some gridlines on overlayed suplots

[archmoj]

Supersedes #7149.

Here is a minimal code change compared to the rather complex solution proposed in #7149 and avoids several potential side effects catch by tests.

Fixes #7144 thanks to debugging sessions with @emilykl and @gvwilson

@plotly/plotly_js
@bpostlethwaite
@stephprobst
@my-tien

[archmoj]

@my-tien and @stephprobst Please use this bundle to test this within your system and let us know.

[archmoj]

@my-tien and @stephprobst Please use this bundle to test this within your system and let us know.

@stephprobst @my-tien were you able to test this bundle? https://output.circle-artifacts.com/output/job/07ec9652-70cc-4287-bfb0-c639ea6b2d39/artifacts/0/dist/plotly.min.js

[stephprobst]

@archmoj - I'm out of office and won't be able to test the package before the end of the week. Same for My-Tien.

[archmoj]

Hi @stephprobst @my-tien
We are wondering if you tested this PR and zorder works as expected to possibly release a patch.
Please confirm.
Thank you!

[stephprobst]

@archmoj: Sorry for the delay in testing. I finally got around to it.

The issue with the gridlines seems to be resolved, but we have a similar situation with the tick labels. Here is a codepen displaying the problem:

https://codepen.io/Djeramon/pen/RwzvXQX

What it looks like in the new test version:

From my understanding, tick labels and ticks should always be drawn on top of the traces, correct?

[stephprobst]

@archmoj: I just noticed, that there is no issue tracking this work anymore. Should I create one? Or will you take care of that? Thanks!

[archmoj]

The inside tick label edge is tracked in #7227.