Backwards incompatible change to String 'first'/'last' complex columns

[clintropolis]

Affected Version

None yet 👍

Description

#12879 introduced compression for ingestion time string 'first' and 'last aggregators, which is cool, however it also changed it so that this is the only way these columns can be written, which is bad because it means that by default any cluster that upgrades can not roll back to an older version.

This code path needs modified to by default write out the existing segment format, and introduce an option to enable to compression. At a future date we could consider enabling the compression by default.