Old space picture is not deleted

## Describe the bug

After changing the space picture the old one is still in the .space folder

## Steps to reproduce
1. Change the picture of a space with an existing picture or upload a new one.
2. Change the space picture a second time

## Expected behavior
The old space picture should be deleted completely (no recycle bin) since it is just a copy.

## Actual behavior
The new space picture is copied to the .space folder but the old one is still there.

## Setup
OCIS 6.61