fix: Removes interval_min validation blocking notification type updates in alert_configuration

[EspenAlbert]

Description

Remove validation that prevented updating alert notifications from types
supporting interval_min to PAGER_DUTY/OPS_GENIE/VICTOR_OPS. Since
interval_min is optional and not preserved via UseStateForUnknown, it will
only be sent to the API if explicitly set in config, allowing updates to
succeed.

Link to any related issue(s): #3869 CLOUDP-358194

Type of change:

• Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR. A migration guide must be created or updated if the new feature will go in a major version.
• Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR. A migration guide must be created or updated.
• This change requires a documentation update
• Documentation fix/enhancement

Required Checklist:

• I have signed the MongoDB CLA
• I have read the contributing guides
• I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code
• If changes include deprecations or removals I have added appropriate changelog entries.
• If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Further comments

[github-actions]

APIx bot: a message has been sent to Docs Slack channel

[EspenAlbert]

Failing test is data federation with s3 access error (investigation going on with upstream team)

[Copilot]

Pull Request Overview

This PR fixes a bug preventing updates from notification types supporting interval_min (e.g., MICROSOFT_TEAMS) to types that don't support it (PAGER_DUTY, OPS_GENIE, VICTOR_OPS). The validation is moved from runtime to schema-level to provide earlier feedback while allowing updates to succeed when interval_min is not explicitly set.

Key changes:

• Replaced runtime validation in NewNotificationList with a schema-level validator
• Added IntervalMinValidator to validate interval_min during Terraform plan phase
• Added comprehensive test coverage for notification type transitions

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
internal/service/alertconfiguration/validator_interval_min.go	Implements new schema-level validator for interval_min attribute
internal/service/alertconfiguration/resource.go	Integrates the validator into the schema definition
internal/service/alertconfiguration/model.go	Removes old runtime validation logic
internal/service/alertconfiguration/resource_test.go	Adds test cases for notification type transitions and validation
.changelog/3882.txt	Documents the bug fix

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