Allow configuration to send PR merged or PR closed to thread only

[ahaslides-don-tran]

Is your feature request related to a problem? Please describe.
Our channel has a lot of notification from team's PR opening and we want everything relate to that PR stay in the thread only. At the moment, whenever PR is closed or merged, it will still send an extra message to the channel

Describe the solution you'd like
We want a configuration so that we can off the channel message for PR closed and PR merged event

Describe alternatives you've considered
N/A

Additional context
N/A