Refactor Nomad Recovery

from an approach that loaded the runners only once at the startup
to a method that will be repeated i.e. if the Nomad Event Stream connection interrupts.

internal/runner/manager.go

@@ -51,8 +51,4 @@ type Accessor interface {
 	// Return signals that the runner is no longer used by the caller and can be claimed by someone else.
 	// The runner is deleted or cleaned up for reuse depending on the used executor.
 	Return(r Runner) error
-
-	// Load fetches all already created runners from the executor and registers them.
-	// It should be called during the startup process (e.g. on creation of the Manager).
-	Load()
 }