Per requirement on T407010

If the user successfully logs in/ creates an account through these, they should land back on the activity tab

Steps to replicate the issue (include links if applicable):

• Open activity while logged-out
• Click "Log-in / create account"
• "Join wikipedia"
• Create a new account

What happens?:

• Confirmation toast appears that account has been created
• The screen remains on the account creation screen with all my details
• The only way to navivate away is pressing "Cancel"

What should have happened instead?:

• After the account is created, I am dropped back onto Activity automatically, logged-into my new account

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
7.8.7 5903

Other information (browser name/version, screenshots, etc.):
iPhone 15
https://drive.google.com/file/d/1c-vO3570VRwI_h7XhDa2vylAlbKocABO/view?usp=sharing