PostHog: Add "team-created" event when teams are automatically created server-side

[joepavitt]

Description

Uses the server-side product API to capture an $ff-team-created event when user's teams are created automatically.

Verified in our test environment:

Related Issue(s)

Closes #4623

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.53%. Comparing base (49321fc) to head (6161d0d).
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4648   +/-   ##
=======================================
  Coverage   78.53%   78.53%           
=======================================
  Files         303      303           
  Lines       14398    14399    +1     
  Branches     3285     3285           
=======================================
+ Hits        11307    11308    +1     
  Misses       3091     3091           

Flag	Coverage Δ
backend	78.53% <100.00%> (+<0.01%)	⬆️

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