MM-46275/MM-46979 Production MPA for web app (#21401)

* MM-46275 Unify various targets for building web app

* MM-46275/MM-46979 Add logic to package boards product static files in CI

* Add error meessage when Boards files can't be found during packaging

* Remove a couple unneeded lines from release.mk

* Decrease size of machine used for setup-focalboard-product

* Revert "Add error meessage when Boards files can't be found during packaging"

This reverts commit f4f46ade0ac4c1ec5525d9b2eae959e13b9aec42.

* Revert "Revert "Add error meessage when Boards files can't be found during packaging""

This reverts commit a0e6420b19c5af0b5ff4706b6abaf8e56f8b3495.

* Fix unrelated email templates

* Skip flaky test

app/platform/service_test.go

@@ -124,6 +124,7 @@ func TestMetrics(t *testing.T) {
 	})
 
 	t.Run("ensure the metrics server is started with advanced metrics", func(t *testing.T) {
+		t.Skip("MM-47635")
 		th := Setup(t, StartMetrics())
 		defer th.TearDown()