Segment Purger cannot purge old segments after schema evolution

[sajjad-moradi]

If a column is added to the schema and there's also an index defined for that column, the older segments which were built by older schema/table config cannot be purged with the following exception:

Cannot create index for column: XYZ because it is not in schema.

This is because SegmentColumnarIndexCreator assumes that schema and table config are always in-sync. That's a valid assumption - other than the old segment scenario mentioned above - because validation put in place in table config rest endpoint makes sure that if an index is added to the table config, that column should be present in the schema.

[sajjad-moradi]

This issue was masked for inverted index columns before index SPI refactoring https://github.com/apache/pinot/pull/10184, because the check for inverted index was bypassed by generate.inverted.index.before.push flag in the table config. But after https://github.com/apache/pinot/pull/10184 was merged, the check now applies for all indices, and now the issue is more common.

[mcvsubbu]

This is a production issue for us