When a progress-message edit hits Telegram flood control (RetryAfter),
can_edit was unconditionally set to False, permanently disabling coalescing
for the rest of the run. Subsequent tool updates were posted as separate
new messages instead of updating the existing progress bubble.
Fix: only set can_edit=False for non-recoverable edit errors. On flood
control, back off by resetting _last_edit_ts so the throttle interval is
respected before the next edit attempt.
Fixes#25188