Revert "AI-438 : added cache key to activity table which is changed each time site rows of that activity are changed (added/removed/updated)"

Rolling back for the time being as this breaks a number of other components
by adding the cacheKey to the DTOs/server tables but not the client-side sqlite
database.

This reverts commit 8b22d763faa87044a7e509ff63f3c1d904113fb1.

Conflicts:

	server/src/main/java/org/activityinfo/legacy/shared/adapter/ActivityUserFormBuilder.java