PHOENIX-7239: Fix issues when data and index have different salt buckets

[haridsv]

This PR includes the following changes:

• Currently IndexMaintainer assumes that both data and index tables have the same number of salt buckets. This change adds a separate field for data table and uses it for constructing the data keys. This fixes the joins between uncovered index and data tables.
• There is a typo in the CDC mutation code path that uses data table to construct the index row key instead of the index table which was throwing off the logic that join the changes to the data rows.
• Test for time range queries has been rewritten to be simpler and also add coverage for the above special DF markers.
• Some of the existing debug code in the CDC IT test has been refactored to be less repetitive.