False ALREADY_EXISTS during Computation creation in Duchy Herald

[renjiezh]

Describe the bug
Both aggregator and worker1 showed the LLv2 computation is existing during creation by the herald. However, there is no entry in the database given the global computation id.
Checking the log, the computation was not created at all. By re-runing the native query in gcp spanner for the reading operation of ComputationToken, it shows no items as well.

Steps to reproduce
Run stress test and there is chance to happen.

Component(s) affected
e.g. Kingdom, Duchy, Reporting Server, testing simulators

Version
v0.5.7-rc2

Environment
QA env

Additional context
global computation id: "eGyFuwTOhdk"