Addons-frontend: The profile picture placeholder from the user info card is too small

[AlexandraMoga]

Follow up for #4283

Prerequisites: user has _not_ set a profile picture to their account

STR:

1. Log in to AMO-dev and select 'View profile' from the user menu
2. Observe the profile image in the user info card

Actual result:
The profile picture placeholder is much smaller than what is depicted in the mocs

Expected result:
The profile picture placeholder has the same dimensions as displayed in the mocs

Notes:

• reproduced on AMO-dev, with FF59, WIn10x64 and Android 7.0

[tofumatt]

😱 Oops, thanks for catching this, should be an easy fix.

[svitlana-galianova]

Hey, I would like to work on this issue

[tofumatt]

Hi @svitlana-galianova, thanks for your interest but I'm going to be taking this issue. 😄 You can have a look at our "contrib: good first bugs" issues to find issues to contribute to.

[svitlana-galianova]

@tofumatt I should have waited for your response...

[tofumatt]

It's cool! In the future you should check the "assigned" field in GitHub; if the issue is assigned it's best not to work on it, but I hadn't actually started so it's okay 😄

[AlexandraMoga]

Verified as fixed on AMO-dev, FF59, Win10x64 and Android 7.0