Make the H2Context store literals in varchars rather than CLOBs. Any literal that exceeds 16k (16,384) bytes should be stored as a CLOB, otherwise as a varchar.

This takes into account H2's insistence that every CLOB, no matter the size, be stored as a file which leads to a huge number of files with a few bytes in them, all allocated at the minimum (4k usually) by the file system.