DBZ-8479 Improve DDL parsing logic

[twthorn]

A few changes to make this DDL logic more fault tolerant

1. Only parse DDLs if that schema history is enabled (otherwise this is unnecessary work)
2. Strip comments to ensure we parse correctly
3. Make table & type fault tolerant so we gracefully handle cases where we didn't parse either

Also fix DBZ-8432

Also dockerfile failing with the apt-key statement so remove that as it's unnecessary

[twthorn]

@jpechane Can you take a look when you get the chance? Thank you

[jpechane]

@twthorn Applied, thanks!