temp/epiphany: drop

Helps #1479 (closed)

The Disable-fullscreen patch from Purism is in principle useful in mobile, as exiting fullscreen is at least troublesome. However, the patch has not been upstreamed and, although we could carry it in alpine for the 42 cycle, the 43 cycle will come with GTK4 support and the patch will not rebase easily. Therefore, instead of waiting 6 months for the drop, lets just drop it now.

@craftyguy you had a good point about the fact that this might break some users. My point here is, epiphany is not the default browser, and the behavior will change anyway after the GTK4 move. So I thought we should rather drop it now than waiting 6 months and maybe breaking even more users :)