fix: correctly release buckets

[dkharms]

Description

One of the nastiest I've ever seen which leads to incorrect accounting of cache-owned memory.

With compaction enabled previous code could overwrite live buckets with other released (or live) buckets leading to x2 cache memory usage.

An example when we lose live buckets:

buckets = [A, B, C, D, E]; toDelete=[A, E]

After the ReleaseBuckets() we end up with buckets = [E, B, C] losing bucket D. This bucket will be eventually released because fraction (bucket's owner) is alive and will suicide (therefore calling Release()) but memory accounting will be broken.

Memory accounting will be broken because the generation bucket belongs to will be evicted therefore memory usage of this bucket will not be accounted.

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