Ability to disable integrated Sentry support

We're using supercronic to run several PHP scripts that maintain their own Sentry integration. When an issue occurrs, we know about it in far more detail than a vague "error running command: exit status 1" produced by supercronic.

I'm looking for a way to disable supercronic's Sentry integration, other than clearing the environment variables; when we clear those, they become unavailable to the PHP scripts invoked by supercronic, and hence their Sentry integration is broken as well.

Of course we can rename our variables as a workaround, but I hope there is an explicit "off" switch in supercronic, telling it to ignore the Sentry environment variables.

Start by locating supercronic's Sentry initialization and the handling of its Sentry environment variables. Add an explicit opt-out while preserving those variables for invoked PHP scripts, then verify that supercronic no longer reports errors to Sentry when the switch is enabled.

Written by the indexing model from the issue text.