[uapp][trace-benchmark] Commonize benchmark handling, improve fidelity

Treat "notrace" and "disabled" tests the same as "normal" tests.

Plus rerun benchmarks multiple times and report min,max,average
to cope with excessive randomness in results.

Tested: trace-benchmark

Change-Id: I0fadfd3845d2038fb0cfc93a9b9eff93d6c373e9

[uapp][trace-benchmark] Reorganize to prepare for streaming mode

- the buffer was filling which invalidates results
- run each benchmark with a fresh buffer
- prepare to support for running under different modes
(oneshot, circular, streaming)
- reduce iteration count so buffer doesn't fill
1,000,000 -> 100,000 shouldn't affect reported results

Tested: trace-benchmark

Change-Id: I171ca856fd488d5430c9e8fba2a4f85f6107a66f