Load balancer counters are reset to 0 if there are load balancer changes

CloudStack uses haproxy in VR to implement the load balancer feature. If there are any load balancer changes (add/remove VMs, add/remove rules, etc), the haproxy configuration will be regenerated and haproxy service in VR will be reloaded.

We've found an issue that counters are reset to 0 after haproxy reload, which is incorrect because the existing connections are remain alive.

Before haproxy reload:

After haproxy reload:

An issue has been created in haproxy community: https://discourse.haproxy.org/t/stats-are-reset-to-0-after-haproxy-reload/8051

Users who monitor the load balancer connections, please pay attention to it.

##### ISSUE TYPE

* Bug Report

##### COMPONENT NAME

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VR
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##### CLOUDSTACK VERSION

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4.17
4.18
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##### CONFIGURATION

Advanced network
load balancer

##### OS / ENVIRONMENT

##### SUMMARY

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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##### ACTUAL RESULTS

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