Searching blocks by `blockHeight` is unusable for small `blockHeights`

[DOBEN]

Task description

Searching blocks by blockHeight is not working for small blockHeights with our front-end UI.

While the search result considers the blockHeigt (https://github.com/Concordium/concordium-scan/blob/ccdscan-backend/0.1.29/backend-rust/src/graphql_api/search_result.rs#L90), there are more than three matches when searching for small blockHeights (e.g. many hashes start with 0 as well). Redesign of the UI behavior to make the search possible since searching for the genesis block is a common behavior.