feat(sdk-platform-java): Add CompositeTracer and CompositeTracerFacto… #550

Job	Run time
filter	59s
build(25) except self-service clients	12m 50s
build(8) for gapic-generator-java	11m 32s
build(21) except self-service clients	12m 18s
build(8) except for gapic-generator-java	4m 22s
build (11)	14m 7s
dependency_analyzer_unit_test	41s
build(8) for showcase	10m 4s
build (17)	13m 6s
showcase (17)	10m 18s
gapic-generator-java-bom	3m 36s
unmanaged_dependency_check	7m 37s
showcase (25)	11m 10s
showcase (21)	10m 23s
showcase (11)	10m 16s
showcase-clirr	0s
	2h 13m 19s

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