[BUGFIX] Table cache_imagesizes is defined twice

The table cache_imagesizes is defined in two files:
t3lib/stddb/tables.sql
typo3/sysext/cms/ext_tables.sql

This is the case for the 4.5 branch as well as the 4.7 branch.
It has been cleaned up in 6.x.

Change-Id: I02f7895ccd25a2404b7742f1706466328869cfce
Resolves: #53758
Releases: 4.7, 4.5
Reviewed-on: https://review.typo3.org/25514
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters