fix: don't release healthchecker during etcd sync due to compaction #15875

Job	Run time
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[a-k]*)	31m 53s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[l-z]*)	30m 14s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/admin t/cli t/config-center-yaml...	24m 16s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/node t/pubsub t/router t/script ...	21m 5s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[a-k]*)	29m 9s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[l-z]*)	28m 3s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/admin t/cli t/config-center-yaml t/cont...	21m 2s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/node t/pubsub t/router t/script t/secre...	23m 43s
	3h 29m 25s

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