MM-49564: Drafts upsert in the Store vs App layer (#22530)

* MM-49564: Upsert in the Store vs App layer

Refactor drafts so that Upserting a draft would happen in the DB and not
in the app layer.

* Fixes mocks

* Fixes tests

* Fixes translations

* Fixes tests

* Update tests

* Fixes tests

* Addresses review comments

- renames Save => Upsert
- removes Sleep from tests

* Fixes flaky test

---------

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

model/draft_test.go

@@ -65,16 +65,3 @@ func TestDraftPreSave(t *testing.T) {
 
 	assert.LessOrEqual(t, o.CreateAt, past)
 }
-
-func TestDraftPreUpdate(t *testing.T) {
-	o := Draft{Message: "test"}
-	o.PreUpdate()
-
-	assert.NotEqual(t, 0, o.UpdateAt)
-
-	past := GetMillis() - 1
-	o = Draft{Message: "test", UpdateAt: past}
-	o.PreSave()
-
-	assert.GreaterOrEqual(t, o.UpdateAt, past)
-}