[HOTFIX] Add dedicated method for formation/formation assignments tim…

[PetarTodorovv]

Description
Currently, we update the entire entity which in some cases can lead to a problem. With this PR we change that logic to use a dedicated method for last_notification_sent_timestamp updates for both formation and formation assignment entities.

Changes proposed in this pull request:

• Introduce a new repo method that will take care to update only the last_notification_sent_timestamp of formations and formation assignments
• Adapt unit tests

Related issue(s)

• Add dedicated method for formation/formation assignments timestamps update #3865
• Add timestamps to formations and formation assignments #3593

Pull Request status

• Implementation
• Unit tests
• Integration tests
• chart/compass/values.yaml is updated
• Mocks are regenerated, using the automated script

[kyma-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ivantenevvasilev

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Needs approval from an approver in each of these files:

• OWNERS [ivantenevvasilev]
• components/director/internal/domain/formation/OWNERS [ivantenevvasilev]
• components/director/internal/domain/formationassignment/OWNERS [ivantenevvasilev]

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