Mark configopaque change as a breaking change #16673

Job	Run time
setup-environment	7s
govulncheck	31s
test-coverage	2m 58s
checks	1m 46s
unittest-matrix (~1.21.5)	2m 33s
unittest-matrix (~1.20.12)	2m 5s
lint	3m 15s
cross-build-collector (darwin, amd64)	36s
cross-build-collector (darwin, arm64)	41s
cross-build-collector (linux, 386)	40s
cross-build-collector (linux, amd64)	41s
cross-build-collector (linux, arm64)	40s
cross-build-collector (linux, ppc64le)	35s
cross-build-collector (linux, arm, 7)	35s
cross-build-collector (linux, s390x)	39s
cross-build-collector (windows, 386)	46s
cross-build-collector (windows, amd64)	45s
unittest	1s
	19m 54s

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