da5bf8016f
Previously the script only showed server stderr — but the bug
investigation needs the CLIENT's runtime traces, which are in the
runner's tee'd stdout (${RUN_DIR}.stdout.log).
awk-narrows the lines to the segment between this testcase's
'Running test case: X' marker and the next one (each testcase runs
a fresh container, so the trace lines between markers are exactly
this testcase's run). Then dumps:
- first 50 [boot] / [interop] / [batch] / [writer.app] lines
- stream_frames=N histogram for the testcase
Useful when debugging a specific testcase failure that requires
seeing the writer's per-drain decisions.