fix popover position

[jancborchardt]

Before & after:

Please review @nextcloud/designers

[tcitworld]

Isn't this somehow related to nextcloud/server#2545 ?

[Ivansss]

LGTM 👍

[skjnldsv]

@jancborchardt you shouldn't need to position the popover if you use the guidelines I put in nextcloud/server#2545 :)

[skjnldsv]

let me check! :)

[skjnldsv]

Indeed, this works. But the best will be to add it like I said in the guidelines:

For référence: the popover menu should be inside the div containing the dots icon.
The required right distance to the border (or padding, whatever you want to use) of the three-dot icon should be 14px (5 for menu margin and 6 for arrow position)