Add timeout to container.exec

[amandahla]

Issue

For some reason, alertmanager and prometheus pods are getting constantly restarted and we couldnt figured out why.

Versions:
Juju 3.1.6
Alertmanager latest/edge 98
Prometheus latest/edge 170

Solution

I was not able to put my finger on it but this PR just adds timeout to the container.exec calls to make sure that this is not leaking and making pebble unresponsive.

Context

Pebble

Testing Instructions

No instructions. It happens randomly.

Release Notes

[sed-i]

Thanks @amandahla and sorry for the long delay.

• Do you still find the timeout useful?
• Could 3 sec be too short?
• Iiuc, a timeout would put the charm in error state. Not sure which approach is best.