Summary:
A better place for our tracing targets to live. These simple apps are used by both experimental probes and Stirling tests.

In sum
//experimental/bpf/tracers/bin -> //demo/client_server_apps
//demos/perf/bcc -> //experimental/bcc_perf

Test Plan: Jenkins

Reviewers: yzhao, zasgar, #engineering

Reviewed By: yzhao, #engineering

Differential Revision: https://phab.corp.pixielabs.ai/D4560

GitOrigin-RevId: 7ee5a9ad28d384cefcd61352510ef67aa1befa9d