GraphSessionManager: session failed to be removed won't be reclaimed

[wey-gu]

As title, a session will be removed from activeSessions_ regardless of its removing attempt being responded normally or not, thus the reclaim will never take care of it.

The following quoted the related discussion initialized by @iiibui:

context: #3567

nebula/src/graph/session/GraphSessionManager.cpp

Lines 140 to 153 in 544c86b

	void GraphSessionManager::removeSession(SessionID id) {
	auto iter = activeSessions_.find(id);
	if (iter == activeSessions_.end()) {
	return;
	}
	iter->second->markAllQueryKilled();
	auto resp = metaClient_->removeSession(id).get();
	if (!resp.ok()) {
	// it will delete by reclaim
	LOG(ERROR) << "Remove session `" << id << "' failed: " << resp.status();
	}
	activeSessions_.erase(iter);
	}

It means meta client will retry in reclaimExpiredSessions? But it will have no chance because session has been removed from activeSessions_.
It means meta server will do reclaim? But I didn't find any “reclaim” related operations in metad.