Simplify db migration toasts (#7063)

xref https://www.mobileread.com/forums/showpost.php?p=4073920&postcount=17

plugins/coverbrowser.koplugin/bookinfomanager.lua

@@ -178,7 +178,7 @@ function BookInfoManager:createDB()
         db_conn:exec(string.format("PRAGMA user_version=%d;", BOOKINFO_DB_VERSION))
 
         -- Say hi!
-        UIManager:show(InfoMessage:new{text =_("BookInfo cache database schema updated."), timeout = 3 })
+        UIManager:show(InfoMessage:new{text =_("Book info cache database updated."), timeout = 3 })
     end
     db_conn:close()
     self.db_created = true

plugins/statistics.koplugin/main.lua

@@ -333,7 +333,7 @@ Do you want to create an empty database?
             end
 
             logger.info("ReaderStatistics: DB migration complete")
-            UIManager:show(InfoMessage:new{text =_("Statistics database schema updated."), timeout = 3 })
+            UIManager:show(InfoMessage:new{text =_("Statistics database updated."), timeout = 3 })
         elseif db_version > DB_SCHEMA_VERSION then
             logger.warn("ReaderStatistics: You appear to be using a database with an unknown schema version:", db_version, "instead of", DB_SCHEMA_VERSION)
             logger.warn("ReaderStatistics: Expect things to break in fun and interesting ways!")