chore(deps): update dependency newrelic/nri-docker to v1.8.15 #7052

Job	Run time
linter-linux / Run Linter	4m 11s
linter-linux / Validate code	35s
harvest-test-linux / Linux harvest tests (ubuntu-20.04)	1m 26s
unit-test-linux / Unit tests for databind	3m 8s
unit-test-linux / Unit tests	7m 12s
build-container / Building containerized agent	13m 41s
harvest-test-macos / MacOS harvest tests (macos-11)	2m 28s
harvest-test-macos / MacOS harvest tests (macos-12)	1m 54s
linter-macos / Lint tests	5m 41s
linter-windows / Lint tests	12m 23s
unit-test-macos / unit tests	7m 54s
proxy-tests-linux / Proxy tests	3m 44s
test-build / Test binary compilation for all (linux) platforms:arch	9m 59s
tools-tests-linux / Tools tests	52s
unit-test-windows / Windows unit tests	7m 9s
unit-test-linux / Coveralls finish	4s
	1h 22m 21s

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