The monitor JSON is now more closely inspected before the actual monitor
is allocated. This prevents creation of monitors without credentials which
was previously possible.
The monitor alteration was also changed to stop and start the monitor only
once instead of stopping and starting after each parameter
modification. This prevents multi-parameter updates from failing due to
monitors seeing a partial set of the new values. Currently only the
`replication_user` and `replication_password` parameters could cause this.
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