Fix Goroutine Leak of Environment Get

that was caused by creating an intermediate environment `fetchedEnvironment` when fetching the environments but not removing it in case that we just copy its configuration to the existing environment.

internal/runner/execution_environment.go

@@ -38,7 +38,8 @@ type ExecutionEnvironment interface {
 	// Register saves this environment at the executor.
 	Register() error
 	// Delete removes this environment and all it's runner from the executor and Poseidon itself.
-	Delete() error
+	// Iff local the environment is just removed from Poseidon without external escalation.
+	Delete(local bool) error
 
 	// Sample returns and removes an arbitrary available runner.
 	// ok is true iff a runner was returned.