Fix regression: Use preview for unsupported images (fix #1408)

[pulsejet]

I think this needs to take priority before NC 25 is released with broken HEIC support.

@skjnldsv @szaimen

[skjnldsv]

/rebase

[skjnldsv]

/compile amend /

[skjnldsv]

/backport to stable25

[skjnldsv]

Btw there will also be this to fix

viewer/src/models/images.js

Lines 29 to 38 in ff759ac

	const mimes = [
	'image/bmp',
	'image/heic',
	'image/heif',
	'image/jpeg',
	'image/png',
	'image/tiff',
	'image/webp',
	'image/x-xbitmap',
	]

I can tackle that a bit later :)

[skjnldsv]

Seems the compile bot didn't want to work.
let me tackle that now then

[skjnldsv]

/backport to stable24

[backportbot-nextcloud]

The backport to stable24 failed. Please do this backport manually.