PC Sampling API: emit info logs instead of error (#53)

* PC Sampling API: emit info logs instead of error

Inside PC sampling API, emit info logs instead of
error logs. The tests verifies status code of each
API call and decide when to skip, instead of relying
on messages in logs.

The samples_processing.cpp test has been removed as it's
not used.

samples/pc_sampling/client.cpp

@@ -77,6 +77,8 @@ tool_init(rocprofiler_client_finalize_t fini_func, void* /*tool_data*/)
     if(client::pcs::gpu_agents.empty())
     {
         *utils::get_output_stream() << "No availabe gpu agents supporting PC sampling" << std::endl;
+        // Emit the message to explicitly skip the sample.
+        std::cerr << "PC sampling unavailable" << std::endl;
         // Exit with no error if none of the GPUs support PC sampling.
         exit(0);
     }