SL-15195 The notification in chat history is multiplied after relogging

indra/llui/llnotifications.cpp

indra/llui/llnotifications.h

indra/newview/llbrowsernotification.cpp

indra/newview/llchiclet.h

indra/newview/llimhandler.cpp

indra/newview/llnotificationalerthandler.cpp

indra/newview/llnotificationgrouphandler.cpp

indra/newview/llnotificationhandler.h

indra/newview/llnotificationhinthandler.cpp

indra/newview/llnotificationofferhandler.cpp

indra/newview/llnotificationscripthandler.cpp

indra/newview/llnotificationtiphandler.cpp

indra/newview/llpersistentnotificationstorage.cpp