Change default LibreOffice icons to Colibre, at least on MATE edition

[Porru]

Default icons used on LibreOffice, at least on MATE community edition, look ugly to me. These are Elementary icon pack:

I propose setting Colibre icons by default, which look prettier and more “fresh” or modern:

If these icons are also default on other editions, I propose to change them.

[Strit]

I think most editions use the default icon pack LibreOffice has…