HDDS-12501. Remove OMKeyInfo from SST files in backup directory.

[SaketaChalamchala]

What changes were proposed in this pull request?

Currently hard links to the SST files are stored in the sst backup directories. The OMKeyInfo in the SST files are not used anywhere.

Proposed optimization would

• Read the SST files and only store the keys including the tombstones into a temporary SST file.
• Acquires a mutex and moves the temporary SST file to the original file, replacing it atomically.

This will significantly reduce the storage footprint and also improve bootstrap time.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-12501

How was this patch tested?

In progress.