Migrates the lastPostsCache from PostStore into cache layer (#13141)

* Some advances

* Partial advances

* Cache moved

* Tests finished

* Removed all test for PostStore (store/sqlstore) related with Cache. This is tested in the cache layer now

store/storetest/post_store.go

@@ -697,7 +697,7 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 		t.Fatal("Missing parent")
 	}
 
-	r2, err := ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 4}, true)
+	r2, err := ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 4}, false)
 	require.Nil(t, err)
 
 	if r2.Order[0] != o5.Id {
@@ -725,7 +725,7 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	}
 
 	// Run once to fill cache
-	_, err = ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 30}, true)
+	_, err = ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 30}, false)
 	require.Nil(t, err)
 
 	o6 := &model.Post{}
@@ -735,17 +735,9 @@ func testPostStoreGetPostsWithDetails(t *testing.T, ss store.Store) {
 	_, err = ss.Post().Save(o6)
 	require.Nil(t, err)
 
-	// Should only be 6 since we hit the cache
-	r3, err := ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 30}, true)
+	r3, err := ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 30}, false)
 	require.Nil(t, err)
-	assert.Equal(t, 6, len(r3.Order))
-
-	ss.Post().InvalidateLastPostTimeCache(o1.ChannelId)
-
-	// Cache was invalidated, we should get all the posts
-	r4, err := ss.Post().GetPosts(model.GetPostsOptions{ChannelId: o1.ChannelId, Page: 0, PerPage: 30}, true)
-	require.Nil(t, err)
-	assert.Equal(t, 7, len(r4.Order))
+	assert.Equal(t, 7, len(r3.Order))
 }
 
 func testPostStoreGetPostsBeforeAfter(t *testing.T, ss store.Store) {