DERBY-6440: Drop connection to foreign database when foreignViews optional tool is unloaded.

backported change #1553269 from trunk to 10.10 branch.



git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/branches/10.10@1630596 13f79535-47bb-0310-9956-ffa450edef68