Collect BackendTLS Policies

[pleshakov]

As a maintainer of NGF
I want to collect the number of used BackendTLS Policies
So that I can understand if that feature is used and how many policies are typically deployed.

Acceptance
Number of BackendTLSPolicies in use is reported in the product telemetry output

[github-actions]

Hi @pleshakov!

Thanks for opening this issue!
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