Handle revisit records in the same way as cdxj-indexer and/or Heritrix

[anjackson]

The crawl-time index is not working for playback because of how revisit records are indexed. See

docker-warcprox/warcprox-plugins/listeners.py

Line 175 in 9b09023

# FIXME! This pushes REVISIT records to the CDX Server with e.g. the original Content Type, not matching

This should be updated to change revisit record handling so they get CDX-indexed in the same way as cdxj-indexer.

[anjackson]

I note that Heritrix3 seems to rely on modifying the content type:

https://github.com/ukwa/ukwa-heritrix/blob/0c21b2756c823697839013254a66f06f80cfea3b/src/main/java/uk/bl/wap/util/OutbackCDXClient.java#L532-L534

We should presumably at least match that, and ideally make sure H3 and warcprox do the same as cdxj-indexer.