## Description 

Load testing shows that there's some perf regression in
`multi_get_transaction_blocks` after
https://github.com/MystenLabs/sui/pull/10913 because some of the
blocking queries such as computing object/balance changes are not
wrapped in spawn_async. This also impacts the perf for
`query_transaction_blocks` which also uses
`multi_get_transaction_blocks` under the hood.

## Next steps
Audit rest of the codebase and make sure all blocking calls are wrapped
in spawn_async

## Test Plan 

Tested against loadgen client and observed that performance regression
is gone

---
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### Type of Change (Check all that apply)

- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

### Release notes