Add config setting to set default User Setting for filter join/leave message (#24047)

* initial submit, join/leave message

* i18n-extract

* additional changes for client config

* add unit tests

* fix unit tests

* change tests to use string not bool

* more unit test fixes

* add and fix unit tests

* revert package-lock

* update unit tests

* Update default_config.ts

* fix unit test

---------

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

server/config/client_test.go

@@ -271,6 +271,28 @@ func TestGetClientConfig(t *testing.T) {
 				"DisableAppBar": "true",
 			},
 		},
+		{
+			"default EnableJoinLeaveMessage",
+			&model.Config{},
+			"tag1",
+			nil,
+			map[string]string{
+				"EnableJoinLeaveMessageByDefault": "true",
+			},
+		},
+		{
+			"disable EnableJoinLeaveMessage",
+			&model.Config{
+				TeamSettings: model.TeamSettings{
+					EnableJoinLeaveMessageByDefault: model.NewBool(false),
+				},
+			},
+			"tag1",
+			nil,
+			map[string]string{
+				"EnableJoinLeaveMessageByDefault": "false",
+			},
+		},
 	}
 
 	for _, testCase := range testCases {