impl(o11y): introduce body.size #181

Job	Run time
filter	1m 1s
build(21) except self-service clients	12m 48s
showcase-clirr	4m 57s
build(8) except for gapic-generator-java	3m 42s
build (11)	13m 52s
gapic-generator-java-bom	5m 10s
build(8) for showcase	4m 36s
dependency_analyzer_unit_test	1m 15s
unmanaged_dependency_check	10m 55s
build(8) for gapic-generator-java	11m 13s
build(25) except self-service clients	12m 23s
build (17)	13m 25s
showcase (21)	8m 23s
showcase (17)	8m 8s
showcase (25)	8m 13s
showcase (11)	8m 16s
	2h 8m 17s

Provide feedback