Merge pull request #18843 from ghouscht/defrag-fixes-backport-3.4 #15549

Job	Run time
test (linux-amd64-fmt)	54s
test (linux-amd64-integration-1-cpu)	9m 49s
test (linux-amd64-integration-2-cpu)	9m 30s
test (linux-amd64-integration-4-cpu)	9m 35s
test (linux-amd64-functional)	7m 52s
test (linux-amd64-unit-4-cpu-race)	46s
test (all-build)	3m 27s
test (linux-amd64-grpcproxy)	15m 13s
test (linux-amd64-e2e)	14m 2s
test (linux-386-unit)	34s
	1h 11m 42s

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