use http2 in http server to support grpc without tls fix #4630

[stamm]

What this PR does / why we need it: to handle grpc without tls

Which issue this PR fixes : fixes #4630

Special notes for your reviewer:

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[APPROVALNOTIFIER] This PR is NOT APPROVED

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[aledbf]

@stamm there is no support for autodetection of http1.x and http2 in nginx itself. Please check
https://forum.nginx.org/read.php?29,278877,278929#msg-278929

With this change, we break http1 without tls.

#3897
#3938
#2465

[stamm]

@aledbf yes, I know. I use separate class for grpc and http request

[aledbf]

@stamm to be clear, I am not in favor of merging this change.

[stamm]

ok, I think we can just patch template to not use function buildHTTPListener