de-duplicate targets from portNumber annotation

[j6nca]

We ran into an issue where sidecar containers (i.e vault agent) get registered as targets due to inheriting the pod's annotations for autodiscovery and resulting in alloy scraping the pod multiple times. This fix does a similar check as the portName check above it, and removes these additional targets if the portNumber annotation is specified and the container does not have a corresponding port number exposed.

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