More notification metrics fixes (#26889)

* Explicitly have the client tell the server when it should expect an ACK

* Don't count missing profile errors for your own posts, added comment

* Fix test

* Make postedAck a parameter in WebSocketClient

* Snapshot fixes

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/platform/web_conn.go

@@ -68,6 +68,7 @@ type WebConnConfig struct {
 	Active       bool
 	ReuseCount   int
 	OriginClient string
+	PostedAck    bool
 
 	// These aren't necessary to be exported to api layer.
 	sequence         int
@@ -89,6 +90,7 @@ type WebConn struct {
 	Locale           string
 	Sequence         int64
 	UserId           string
+	PostedAck        bool
 
 	allChannelMembers         map[string]string
 	lastAllChannelMembersTime int64
@@ -234,6 +236,7 @@ func (ps *PlatformService) NewWebConn(cfg *WebConnConfig, suite SuiteIFace, runn
 		UserId:             cfg.Session.UserId,
 		T:                  cfg.TFunc,
 		Locale:             cfg.Locale,
+		PostedAck:          cfg.PostedAck,
 		reuseCount:         cfg.ReuseCount,
 		endWritePump:       make(chan struct{}),
 		pumpFinished:       make(chan struct{}),