feat(billing): Remove AUTO_SEAT_UPGRADE_PLANS setting

[khvn26]

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Changes

In this PR, we remove the AUTO_SEAT_UPGRADE_PLANS setting in favour of centralised SubscriptionPlanFamily.get_by_plan_id logic.

How did you test this code?

Made sure all relevant unit tests pass without the setting present.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.61%. Comparing base (c7584d7) to head (1271758).
Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5343   +/-   ##
=======================================
  Coverage   97.61%   97.61%           
=======================================
  Files        1237     1237           
  Lines       42918    42968   +50     
=======================================
+ Hits        41894    41945   +51     
+ Misses       1024     1023    -1     

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[Zaimwa9]

So i'm seeing

class SubscriptionPlanFamily(Enum):
    FREE = "FREE"
    START_UP = "START_UP"
    SCALE_UP = "SCALE_UP"
    ENTERPRISE = "ENTERPRISE"

But I don't see the plan on the pricing page. Is it a custom in between start-up and enterprise?

[khvn26]

Good question 👍 Our plan lineup has been revised to exclude scale-up for new customers, but we still support existing scale-up users.

[Zaimwa9]

The tests seem to cover the different cases. If I summarize how we do now:
If subscription is scale-up-xx
Organisation don't have fixed user limits but when adding a new one:

• We charge the seat
• if payment fails => failure and user can't join
• otherwise +1 user ?

Could you let me know when it's on staging to use it to start manipulating chargebee 👍 ?