Occasional slowdown in runtime

[bowenwang1996]

It appears that runtime very occasionally slows down significantly after finish processing all receipts:

• See example here
• Discussion on zulip.

It seems that either runtime::check_balance or TrieUpdate::finalize takes a very long time in those cases. We should investigate and understand what the root causes are so that validators would not miss blocks or chunks as a result

[bowenwang1996]

Looks like the culprit is TrieUpdate::finalize. When there are a lot of receipts, it can take a long time. Discussion thread on zulip

[akhi3030]

CC: @Ekleog-NEAR