HPCC-12347 Refresh graph only merged new data into control

Refresh graph should re-fetch the data and do a clean load.

Fixes HPCC-12347

Signed-off-by: Gordon Smith <gordonjsmith@gmail.com>
Merge pull request #6545 from GordonSmith/HPCC-12347

HPCC-12347 Refresh graph only merged new data into control

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>