Fix color of app menu entries and background color

[susnux]

• Resolves: [Bug]: NC 28.0.2 - Icons in toolbar are black instead of white #43298

Summary

This fixes two issues:

1. a96a7f0 introduced a regression because it applied the color invert filter on the text which is already colored correctly (primary-text).
2. Most of the time the background color is color-primary but for some shipped background images the primary color does not lead to the same text color -> app menu names and the right header menu entries have wrong colors.

Especially try following: Set default background -> white text -> click "remove image" -> suddenly the app menu color is black on the same blue.

A better solution will be #42977 but for the moment this one is simpler.

before	after

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[susnux]

/backport to stable28

[skjnldsv]

🙈

[skjnldsv]

@AndyScherzinger the failure was related, revert in #43401

[Jerome-Herbinet]

Hi @AndyScherzinger
Not sure to understand this PR's history.
I still have the problem with Nextcloud 28.0.6.
Is this normal ? Bad fix or revert ? ... or will it be only fixed from NC 29?
Thanks

[AndyScherzinger]

@Jerome-Herbinet according to the backport at #43392 it is shipped with 28.0.3, so if you already face issues in later versions of 28 I expect it to either be a regression or a new bug. So best to raise that in a new ticket since the source of the issue might be different.