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/public/model/config_test.go

@@ -335,6 +335,14 @@ func TestTeamSettingsIsValidSiteNameEmpty(t *testing.T) {
 	require.Nil(t, c1.TeamSettings.isValid())
 }
 
+func TestTeamSettingsDefaultJoinLeaveMessage(t *testing.T) {
+	c1 := Config{}
+	c1.SetDefaults()
+
+	// should default to true
+	require.Equal(t, NewBool(true), c1.TeamSettings.EnableJoinLeaveMessageByDefault)
+}
+
 func TestMessageExportSettingsIsValidEnableExportNotSet(t *testing.T) {
 	mes := &MessageExportSettings{}