HDDS-12655. Optimize Recon Container Mismatch API while getting containerInfos & ContainerMetadata. - ( OM Changes )

[ArafatKhan2198]

What changes were proposed in this pull request?

The existing mismatch API was inefficient because it looked into the containerKeyPrefix table for all containers, which required examining many more keys than necessary. This was especially problematic when only checking for container presence rather than needing full container metadata. The original approach used complex dual-iterator logic with sorting and comparison operations, leading to poor performance and unnecessary deserialization.

Proposed Changes

1. Removed peekNextKey() Functionality
   The pull request removes the peekNextKey() method from the SeekableIterator interface and updates the ContainerMetadataIterator to remove peek functionality. The ContainerEndpoint logic was modified to use simple next() calls instead of peek operations, and the corresponding test method testContainerIteratorPeekNextKey() was removed.
2. Completely Overhauled SCM Case Logic
   The SCM case (missing in SCM - data loss scenario) was completely rewritten following reviewer feedback. The old approach used complex dual-iterator logic with sorting and comparison operations. The new approach loads all SCM containers into a HashMap for fast O(1) lookups, then iterates over OM containers using only the containerKeyCountTable to avoid unnecessary deserialization. This eliminates the need for complex iterator comparisons and seeking operations.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-12655

How was this patch tested?

Unit tests

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