HPCC-12349 tojson.xml regression key has extra characters

Was matching output of an error in unicode handling.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #6502 from afishbeck/tojsonUnicode

HPCC-12349 Fix tojson.xml key related to issue outputting extra characters for unicode strings

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>