[BUGFIX] Add SQL Index to Processed Files DB table

Added index to original,task_type,configurationsha1
this improves performance for non-cached pages and
backend calls

Resolves: #54729
Releases: 6.2
Change-Id: I2ecfe62c64b89078da5c04ee708ea3c343d4fc9a
Reviewed-on: https://review.typo3.org/26628
Reviewed-by: Oliver Klee
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack