Registered runners should unregister by default

Overview

We have unregisterRunners that in !231 (comment 351677299) and commenting it out, so that we preserve (for backward compatibility reasons) the behavior that we have where:

• Currently by default unregisterRunners: true is set and if you use a runnerRegistrationToken your runner gets unregistered. If you use a secret the runner is not unregistered, even though unregisterRunners: true is set.
• After the merge by default unregisterRunners: true is unset and if you use a runnerRegistrationToken your runner gets unregistered. If you use a secret the runner is not unregistered, unless you actively change the default configuration.

This behavior is confusing and requires special care. This is also confusing for users who use the helm chart.

Proposal

Have unregisterRunners: true all the time, making the behavior consistent and clear no matter when type of registration token is used.