Expose Watcher configuration through configMap

[enarha]

The completedRunGracePeriod controlling for how long the pipelineruns are kept around before being pruned is a high level configuration option useful for the user. It is implemented as Watcher's cmd line option and it's "too hidden" for the user to discover and hard to change. Ideally it's be set in config and exposed through configMap, the same way things are done for the api component.
Furthermore, there is the Tekton pruner, which makes for 2 pruners for the same types of objects and it'll be good user experience if the user can control them via the same interface (TektonConfig?). The latter won't be always possible because users can either deploy Tekton via the operator or using manifests for each project separately, yet this is something to consider.

Another good example of Watcher parameter to expose through a config is the handling of the owner reference annotations.

[sayan-biswas]

Agreed.
I think we should move the configs to Knative config loader. That will not only allow the configuration to be handled by configMap, it can also allow user to change some of the relevant configurations during runtime.

[enarha]

/assign @enarha