[EC2SpotManager] Only write unique status messages.
[EC2SpotManager] Only write unique status messages.

Since parts of the algorithm run even when critical pool/provider
status messages exist, we should ensure that those messages are only
written on the first attempt.

MozillaSecurity/FuzzManager,MozillaSecurity/FuzzManager,MozillaSecurity/FuzzManager,MozillaSecurity/FuzzManager