deps: update netty dependencies to v4.1.109.final #6120

Job	Run time
build (11)	12m 16s
build(21) except self-service clients	11m 29s
build (17)	12m 15s
build(8) for gapic-generator-java	10m 35s
compatibility	1m 29s
gapic-generator-java-bom	1m 47s
dependency_analyzer_unit_test	14s
lint	26s
showcase (11)	3m 55s
showcase-clirr	2m 59s
showcase (17)	4m 9s
showcase-native	8m 8s
unmanaged_dependency_check	3m 56s
build(8) except for gapic-generator-java	3m 57s
	1h 17m 35s

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