Set a default Toleration value

There are several issues including this one #266 where the users get the error error connecting to provider "aws" due to the POD tolerations.

I think that it should be set by default [{"operator": "Exists"}] as it is on secrets-store-csi-driver

This will save a ton of debugging time to a lot of people.

Update the troubleshooting section with this issue is also a good option, in case there is not possible to update the default value on the helm chart.