Implement solution for when no active zones in CHUNK LRU

[johnramsden]

https://github.com/johnramsden/ZNWorkload/blob/425393f5915e15c68f3223571214996c94fcc0fe/src/eviction/chunk.c#L105-L108

Potential soln:

• Load a Zone into a ram buffer, reset and then write it out into the erased zone
• No extra zones needed
• Use extra 1GiB buffer, can pre-allocate, add to chunk evict struct

[2a46m4]

I can work on this issue