intent: a decision whose then:/else: targets itself is not refused like next: <self> is (#7226 follow-up)

[delchev]

Describe the bug

PR #7274 (#7226) refuses next: <self> on a process step at parse:

// parser/IntentParser.java:6344-6353
if (next.equals(step.getName())) {
    issues.add("... `next` targets itself - a self-loop that never advances");

The same spin exists one key over and is still accepted: a decision whose then: or else: names the decision itself. checkDecisionTarget (:6869-6875) checks only that the target exists. An exclusive gateway has no wait state, so - { name: rated, kind: decision, if: ..., then: rated, else: done } emits a sequence flow from the gateway to itself and Flowable spins on it exactly as the next self-loop did - which is what made the ResilienceBpmnTest fixture bug worth a parse rule in the first place.

Not proposing the same for onError: <self> (that is an unbounded retry; retry: exists for it, but the semantics are arguable) nor for a timer boundary's then: <self> on a userTask (re-open the task - a legitimate pattern that must stay legal). Multi-step cycles through a wait state are legitimate and correctly untouched.

Expected

then:/else: of a decision naming the decision itself is refused with the same sentence as next.