[Chore]: Investigate DynamoDB GSIs throttling impact

[matteojug]

Chore - Investigate DynamoDB GSIs possible throttling

1. Description

Emily uses DynamoDB tables with Global Secondary Indexes, and those are susceptible to throttling under high traffic conditions if such traffic exceeds the provisioned capacity. Note that we use those for deposits/withdrawal using the status as partitionKey, so all request with the same status end up in the same partition.

We should investigate the impact of such throttling, and if it's something we want to address or not.