Implement test for global congestion control

[aborg-dev]

This is a continuation of work in #8920

We want a test case that will evaluate congestion in a multi-shard environment.
The main difference from the local congestion control is that the load that results in the congestion will be coming from other shards to the hot shard as incoming receipts.

We will reuse the same Locust setup, extending the workload defined in https://github.com/near/nearcore/blob/a5ede1d1cd54906ac91cbb614028b5323ddee0c0/pytest/tests/loadtest/locust/common/congestion.py.

The test should check that after a bursty load that is over the capacity of all shards, the transactions are properly queued up and eventually executed.

A good starting point will be reusing ComputeSum transaction, but issuing the requests to it from accounts on different shards.

[aborg-dev]

This work is superseded with near/NEPs#539.