feat: add custom_metric for dynamic batching #18886

Job	Run time
check-black	3m 8s
build-wheels (ubuntu-latest, 3.7, cp37-cp37m)	1m 31s
build-wheels (ubuntu-latest, 3.8, cp38-cp38)	1m 24s
build-wheels (ubuntu-latest, 3.9, cp39-cp39)	1m 24s
check-docstring	5m 37s
build-wheels (ubuntu-latest, 3.10, cp310-cp310)	1m 22s
build-wheels (ubuntu-latest, 3.11, cp311-cp311)	1m 22s
build-wheels (macos-latest, 3.8, 38, macosx_x86_64, x86_64, amd64)	2m 25s
code-injection	1m 11s
build-wheels (macos-latest, 3.9, 39, macosx_x86_64, x86_64, amd64)	2m 5s
build-wheels (macos-latest, 3.10, 310, macosx_x86_64, x86_64, amd64)	1m 35s
build-wheels (macos-latest, 3.11, 311, macosx_x86_64, x86_64, amd64)	1m 55s
commit-lint	3m 17s
build-wheels (macos-latest, 3.8, 38, macosx_arm64, arm64, arm64)	2m 7s
build-wheels (macos-latest, 3.9, 39, macosx_arm64, arm64, arm64)	1m 23s
build-wheels (macos-latest, 3.10, 310, macosx_arm64, arm64, arm64)	1m 17s
lint-flake-8	12s
build-wheels (macos-latest, 3.11, 311, macosx_arm64, arm64, arm64)	1m 21s
k8s-flow-test	0s
docker-image-test	0s
k8s-deployment-test	0s
hub-test	0s
k8s-failures-test	0s
k8s-graceful-test	0s
docker-compose-test	0s
import-test	0s
k8s-otel-test	0s
prep-testbed	0s
install-jina-ecosystem-test	0s
stateful-docarray-v-two-test	0s
core-test	0s
docarray-v-two-test	0s
success-all-test	3s
	34m 39s

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