Server stuck in `Reserved` if no `ServerClaim` exists

[defo89]

Describe the bug
Server might be stuck in Reserved state and have serverClaimRef which does not exist.

Cleanup and state transition might fail because we check for serverBootConfig to early:
https://github.com/ironcore-dev/metal-operator/blob/main/internal/controller/server_controller.go#L418-L422

Expected behavior
serverClaimRef is removed if claim does not exist, Server can be used for any other valid matching claim.

[coderabbitai]

🔗 Related PRs

#615 - Set maintenance needed label on ServerClaim [merged]
#632 - Enqueue multiple ServerClaims on Server changes [merged]

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