fix(kafka-pubsub): restore `pb.state` appropriately #2266

Job	Run time
run ci on redhat ubi (lua-resty-worker-events, t/plugin/[a-k]*)	50s
run ci on redhat ubi (lua-resty-worker-events, t/plugin/[l-z]*)	54s
run ci on redhat ubi (lua-resty-worker-events, t/admin t/cli t/config-center-yaml t/control t/cor...	52s
run ci on redhat ubi (lua-resty-worker-events, t/node t/pubsub t/router t/script t/secret t/strea...	53s
run ci on redhat ubi (lua-resty-events, t/plugin/[a-k]*)	52s
run ci on redhat ubi (lua-resty-events, t/plugin/[l-z]*)	54s
run ci on redhat ubi (lua-resty-events, t/admin t/cli t/config-center-yaml t/control t/core t/deb...	53s
run ci on redhat ubi (lua-resty-events, t/node t/pubsub t/router t/script t/secret t/stream-node ...	53s
	7m 1s

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