Configure a prometheus endpoint which serves metrics about the
otel-collector itself. Also adds a prom_scraper_config so promscraper
scrapes the metrics.

Signed-off-by: Rebecca Roberts <[email protected]>

When OTel Collector jobs are disabled, don't output any prom scraper
configuration so that the prom scraper skips over these jobs. This
avoids continual error messages logged by the prom scraper when it can't
scrape a destination.

Signed-off-by: Andrew Crump <[email protected]>

Since we already dropped exact parity with OTel Collector settings with
`ingress.grpc.tls.*`, we think it's preferable to remove the `service.`
prefix from telemetry properties in the OTel Collector jobs.

Signed-off-by: Carson Long <[email protected]>