Add config to send crash reports which are occurred after kwatch started.

[Warashi]

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

I'm always frustrated when kwatch pod is restarted because many crash reports are resent to Slack.

Describe the solution you'd like A clear and concise description of what you want to happen.

Add config to send crash reports which are occurred after kwatch started.

[blochsbek]

Yeah this is a big one, def need.

[blochsbek]

Since it already grabs the time that kwatch starts, can it just only pull things after that "time"....