Account activation link does not work for customers

Issue Summary

When a new customer added to the project, receives account activation mail in order to reset the password. If the customer clicks the activation link he gets an error that You do not have permission to view this Portal

Tested on lower version 8.20.11 and it works fine.

This is reproducible on Data Center: yes

Steps to Reproduce

1. Disable the public signup from Application -> JIRA SERVICE MANAGEMENT -> Configuration  
2. Set the customer permission to Customers who are added to this service project
   
3. Create a customer from the user management console
4. Create an organisation in the service management project and add the customer to the organisation
5. Customer receives an email with the mentioned activation link
6. Customer clicks on this link in order to reset the password(make sure when link is clicked it opens in incognito/different browser as if it gets opened in the same browser then it picks the Admin session)

Expected Results

The customer receives an email with the prompt to activate the Jira account. If the customer clicks the activation link he will get an option to set up the password and log in.

Actual Results

The customer receives an email with the prompt to activate the Jira account. If the customer clicks the activation link he gets an error that You do not have permission to view this Portal

Workaround

Inform the users to follow forget password flow for users receiving the activation link.

• User can click Login here> forgot password > and set a password for their account.