Automatic merge from submit-queue (batch tested with PRs 38597, 38570)

Logging request / response body should not allocate

Putting string(data) in the critical path causes an allocation which can
be very large, and happens regardless of whether logging is enabled.

Also, use the more sophisticated logging of body output that avoids
causing quoting of JSON output (current behavior is "{\"key\":...}" and
should be {"key":...} for readability).

@wojtek-t reduces large heap allocations on updates