Bump github.com/signalfx/signalfx-go/signalflow/v2 from 2.1.0 to 2.1.1 in /tests #6855

Job	Run time
setup-environment	3m 10s
lint	25m 21s
gofmt	6m 15s
test	10m 45s
generate-metrics	3m 40s
tidy	1m 39s
coverage	5m 39s
cross-compile (binaries-darwin_amd64)	4m 5s
cross-compile (binaries-darwin_arm64)	4m 5s
cross-compile (binaries-linux_amd64)	7m 0s
cross-compile (binaries-linux_arm64)	8m 1s
cross-compile (binaries-windows_amd64)	4m 6s
cross-compile (binaries-linux_ppc64le)	8m 0s
	1h 31m 46s

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