Do not store modified email when deduping email list

[knolleary]

Fixes #4222

Description

A previous fix (#2543) was applied to de-duplicate the emails provided in the Team Invite flow, including stripping . from gmail addresses.

However, stripping the . lead to an unexpected behaviour:

1. User invites foo.bar@gmail.com
2. Owner of that email receives it at foobar@gmail.com, follows the link
3. Sees the email field pre-filled as foobar@gmail.com - corrects it to their preferred address foo.bar@gmail.com
4. They sign-up, but with a different email than stored in the team invite - so they don't get added to the team

This fixes this scenario by still deduplicating the emails via their canonical version, but it then stores the unaltered email rather than the canonical version. This better aligns with the expected result.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.64%. Comparing base (e1cc16f) to head (856039c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4232   +/-   ##
=======================================
  Coverage   78.64%   78.64%           
=======================================
  Files         286      286           
  Lines       13119    13123    +4     
  Branches     2934     2935    +1     
=======================================
+ Hits        10317    10321    +4     
  Misses       2802     2802           

Flag	Coverage Δ
backend	78.64% <100.00%> (+<0.01%)	⬆️

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