MM-57786 Fix Shared Channels plugin api (#26753)

* always ping on plugin registration; SharedChannel.IsValid allow no team for GM

* wait for services to start before ping

* ping plugin remotes synchronously on startup

* remove the waitForInterClusterServices stuff

* don't set remoteid when inviting remote to channel

* Update server/public/model/remote_cluster_test.go

Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

* address review comments

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

server/public/model/remote_cluster_test.go

@@ -136,3 +136,25 @@ func makeInvite(url string) RemoteClusterInvite {
 		Token:        NewId(),
 	}
 }
+
+func TestNewIDFromBytes(t *testing.T) {
+	tests := []struct {
+		name string
+		ss   string
+	}{
+		{name: "empty", ss: ""},
+		{name: "very short", ss: "x"},
+		{name: "normal", ss: "com.mattermost.msteams-sync"},
+		{name: "long", ss: "com.mattermost.msteams-synccom.mattermost.msteams-synccom.mattermost.msteams-synccom.mattermost.msteams-sync"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got1 := newIDFromBytes([]byte(tt.ss))
+
+			assert.True(t, IsValidId(got1), "not a valid id")
+
+			got2 := newIDFromBytes([]byte(tt.ss))
+			assert.Equal(t, got1, got2, "newIDFromBytes must generate same id for same inputs")
+		})
+	}
+}