Reduce the memory consumption required by Compaction

[ShiKaiWi]

Describe This Problem

Current compaction procedure consumes much more memory than expected. The theoretical usage of memory should be a little more than the total size of all the input ssts, but now the actual consumption is 4-10 times theoretical value.

Proposal

The reasons for the high memory consumption, I can come up with these:

• Build sst file in more resource friendly way #486
• The input data which will be invalidated later should be put back into the cache;
• Some indexes (e.g. bloom filter) are not necessary to be loaded because predicates won't be used by compaction.

Additional Context

No response

[jiacai2050]

Fixed in main.