[BUILD] Transitive dependency issue with the otlp http exporter

[astitcher]

Describe your environment
Ubuntu latest and Fedora 38

Steps to reproduce
Build main (or 1.9.0) with cmake with -DWITH_OTLP=on -DWITH_OTLP_HTTP=on -DWITH_OTLP_GRPC=off either with static or shared libraries (I'm really mostly interested in shared libs though).

run 'make' then 'make install' installing in a place that the subsequent qpid-proton build will find.

Then configure qpid-proton with the appropriate install prefix

What is the expected behavior?
No error!

What is the actual behavior?
...
CMake Error at cpp/examples/CMakeLists.txt:62 (add_executable):
Target "tracing_client" links to target "protobuf::libprotobuf" but the
target was not found. Perhaps a find_package() call is missing for an
IMPORTED target, or an ALIAS target is missing?

CMake Error at cpp/examples/CMakeLists.txt:62 (add_executable):
Target "tracing_client" links to target "nlohmann_json::nlohmann_json" but
the target was not found. Perhaps a find_package() call is missing for an
IMPORTED target, or an ALIAS target is missing?

CMake Error at cpp/examples/CMakeLists.txt:62 (add_executable):
Target "tracing_server" links to target "protobuf::libprotobuf" but the
target was not found. Perhaps a find_package() call is missing for an
IMPORTED target, or an ALIAS target is missing?

CMake Error at cpp/examples/CMakeLists.txt:62 (add_executable):
Target "tracing_server" links to target "nlohmann_json::nlohmann_json" but
the target was not found. Perhaps a find_package() call is missing for an
IMPORTED target, or an ALIAS target is missing?
...

Additional context
Here is a Dockerfile that builds under ubuntu latest demonstrating the problem:
Dockerfile.txt

Looking at the installed exporter header files for the otlp http exporter there is no actual reference to either nlohmann_json headers or protobuf headersand so I can see no reason why ot defines them as public dependencies (or even why they would be interface deps).