ZBX-22307 restructured databased directories and in the New directory structure for database-related files as a first example the double.sql file is presented

which does not exist, since it was removed in ZBXNEXT-8324 in the same 7.0.0 version.

In other words, upgrade notes for 7.0.0 contain 2 self-exclusive things: removal of double.sql and mentioning that double.sql is present in the new directory structure.

double.sql from the upgrade notes needs to be either
1) completely removed
2) removed from the "current" structure (with possible note that it is removed because of another ticket)