[EC-144] Fix stripe revert logic

[djsmith85]

Type of change

• Bug fix
• New feature development
• Tech debt (refactoring, code cleanup, dependency upgrades, etc)
• Build/deploy pipeline (DevOps)
• Other

Objective

Fixes an issue where reverting a subscription update would fail.

Props to @MGibson1 for pairing and supporting on this!!

Code changes

• src/Core/Models/Business/SubscriptionUpdate.cs:
  • Save previousSeats during a seat expansion subscription update to decide in case of a revert to either update the existing subscription item (Teams/Enterprise) or delete it.
  • Save previousStorage during a storage expansion subscription update to decide in case of a revert to either update the existing subscription item (storage-gb-XXX) or delete it.
• src/Core/Services/Implementations/StripePaymentService.cs:
  • Adding a try catch around the Subscription-Update/-Revert as the revert previously threw but was swallowed

Before you submit

• I have checked for formatting errors (dotnet tool run dotnet-format --check) (required)
• If making database changes - I have also updated Entity Framework queries and/or migrations
• I have added unit tests where it makes sense to do so (encouraged but not required)
• This change requires a documentation update (notify the documentation team)
• This change has particular deployment requirements (notify the DevOps team)

[MGibson1]

Since we paired on this, feel free to ask for more reviews, but I'll go ahead and approve.

Also, nice job on the QA test notes (I know most people here can't read them since we moved them to jira, but trust me, they're thorough)

[justindbaur]

Just one question.

[justindbaur]

Looks great!