Fix: skip deallocations when burning in grace period

[shark0der]

Context

When a burn is triggered while the cover is in grace period the deallocation is redundant since it will be done when the bucket expiration is processed.

Changes proposed in this pull request

The newly added code skips deallocations if the cover is expired.

Test plan

Added a test to ensure the allocations stay the same.

Checklist

• [x] Rebased the base branch
• [x] Attached corresponding Github issue
• [x] Prefixed the name with the type of change (i.e. feat, chore, test)
• [x] Performed a self-review of my own code
• [x] Followed the style guidelines of this project
• [ ] Made corresponding changes to the documentation
• [x] Didn't generate new warnings
• [x] Didn't generate failures on existing tests
• [x] Added tests that prove my fix is effective or that my feature works

Review

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• :hammer: = I believe this should be changed.
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• :rocket: = Feedback

[rackstar]

marking as draft so it won't be accidentally merged while on audit