Different subscription icons in my-account since last changes

[kimsible]

Since https://github.com/Chocobozzz/PeerTube/pull/2977/files some icons has been updated like the subscription icon to be common with the one in the left menu :

And since the general user-menu effects on this PR : #2971, this icon has also been used on sub-titles.

At last, since this last commit kimsible@aa91835 on this PR #2966 about the limitation of upload form and user menus, a small refacto has been made on the user sub-menu and re-injected the old icon :

Anyway what icon is used, the same ones on sub-titles and sub-menu should be used.

[rigelk]

fixed by #3031.