Clean-up work done for temporary storage increase

The https://gitlab.com/groups/gitlab-org/-/epics/3941+ epic has been closed as won't do, this issue is to clean-up the work done in that epic.

The work has been implemented behind temporary_storage_increase feature flag.

Additionally, we might want to investigate if we can deprecate is_temporary_storage_increase_enabled and temporary_storage_increase_ends_on. From memory, I remember this started being implemented but we never finished. #416660 (closed)

Some relevant MRs:

• Add temporary storage increase modal (!36374 - merged)
• Expose temporary storage increase end date (!36495 - merged)
• Use temporary storage increase date (!37511 - merged)

Development steps

MR	Description	Milestone	Status
!136202 (merged)	Deprecating temporary storage increase graphql fields	%16.7	✅
!151386 (merged)	Remove is_temporary_storage_increase_enabled and temporary_storage_increase_ends_on graphql fields	%17.0	✅
!135602	Removing temporary_storage_increase_ends_on column from db schema	%17.7	⏳ pending
!135604	Removing ignoring temporary_storage_increase_ends_on column in the model	%17.8	⏳ pending