FaultInjector_UpdateHashEntry() was using FaultInjector_InsertHashEntry(), which
ends-up adding entry if not present without incrementing
`faultInjectorShmem->faultInjectorSlots`. This causes inconsistency, plus also
sometimes encounters "FailedAssertion(""!(faultInjectorShmem->faultInjectorSlots
== 0)""," during fault inject reset, as goes negative. Fixing the same by using
FaultInjector_LookupHashEntry() instead as that's what
FaultInjector_UpdateHashEntry() needs.

Scenario the Assertion was hitting:
gpfaultinjector -f all -m async -y resume -r primary -H ALL
gpfaultinjector -f all -m async -y reset -r primary -H ALL