Made agent state consistent with forwarded updates.
Made agent state consistent with forwarded updates.

When the agent handles an `UpdateOperationStatusMessage` from a resource
provider, it injects its own ID which is (at least conceptually) unknown
to the resource provider before forwarding the message to the master,
and also updates its own tracking for the operation.

This patch makes sure that we first mutate the message before handing it
on for updating the internal operation tracking, while previously we
used the unmodified message. Always using the same message reduces error
potential if in future changes we e.g., introduce agent operation status
update managers.

Review: https://reviews.apache.org/r/69458/

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