otel: tls endpoint and otel in serve mode

[TheRayquaza]

I found a couple of issues when using a TLS OTEL endpoint:

TLS certificates for OTEL

before: can't be verified by the shim

OpenTelemetry trace error occurred. error sending request for url (https://...): error trying to connect: 
error:0A000086:SSL routines:tls_post_process_server_certificate:certificate verify 
failed:ssl/statem/statem_clnt.c:2124: (self-signed certificate in certificate chain)

fix: added the rustls-native-certs package to verify certificates

OTEL configuration failure

before: when the OTEL configuration is invalid, the shim fails and never return the pod uuid back to containerd

Failed to create pod sandbox: rpc error: code = Unknown desc = failed to start sandbox
"3cb59679bc83014eeb5e249b740b507965ef6928d77dbf5ccfa85ab103dd9e64": failed to create containerd task: 
failed to start shim: start failed: failed to create TTRPC connection: unsupported protocol:
OpenTelemetry trace error occurred. error sending request for url (https//...

fix: OTEL configuration is loaded only in serve mode, invalid configuration is just ignored