cmake: replace opentracing-cpp with opentelemetry-cpp

cmake: replace opentracing-cpp with opentelemetry-cpp

we build and use targets needed for jaeger to work with opentelemetry
referring:
https://github.com/open-telemetry/opentelemetry-cpp/blob/main/examples/jaeger/CMakeLists.txt

right now we need a patch for using thrift from distro packages, hence
we are using GIT_FETCH based externalProject method, for development
purpose, which will be replace by more reliable method in future.

NOTE: phase 1, still needs to be tested.

Signed-off-by: Deepika Upadhyay <dupadhya@redhat.com>