CI is substituting the generated manifests

[kimwnasptd]

This came up from #160 (comment)

Our CI should only be changing the image that is used by a manifest file, with the locally built one. But, right now, the deploy_component.sh is also substituting other fields instead of just the image

dashboard/testing/gh-actions/deploy_component.sh

Lines 46 to 51 in 6eb7103

	| sed 's/$(podDefaultsServiceName)/poddefaults-webhook-service/g' \
	| sed 's/$(podDefaultsNamespace)/kubeflow/g' \
	| sed "s|\$(CD_NAMESPACE)|${CD_NAMESPACE:-kubeflow}|g" \
	| sed "s|\$(CD_CLUSTER_DOMAIN)|${CD_CLUSTER_DOMAIN:-cluster.local}|g" \
	| sed "s|CD_NAMESPACE_PLACEHOLDER|${CD_NAMESPACE_PLACEHOLDER:-kubeflow}|g" \
	| sed "s|CD_CLUSTER_DOMAIN_PLACEHOLDER|${CD_CLUSTER_DOMAIN_PLACEHOLDER:-cluster.local}|g" \

This can lead to masking errors, as we saw in #160 (comment), in which the manifests had a bug yet our CI never caught this.

cc @juliusvonkohout @kunal-511

[kimwnasptd]

The PodDefault substitution will be fixed in the linked PR.

Do we need the other substitutions?