tree items with many children hang browser

[artemmufazalov]

https://nda.ya.ru/t/D4Zkbcn176xy6F

[artemmufazalov]

Previously all child items was dispatched to store in 1 dispatch:

ydb-embedded-ui/src/containers/Tenant/Schema/SchemaTree/SchemaTree.tsx

Line 54 in 6a3a594

dispatch(preloadSchemas(preloadedData));

Currently, there is a dispatch for every child item: https://github.com/ydb-platform/ydb-embedded-ui/blob/main/src/store/reducers/schema/schema.ts#L84

Appeared after this PR: #948