Upgrade to Prometheus 3.0

[ptodev]

Prometheus 3.0 was released in November 2024. Given that Alloy includes native Prometheus pipelines, it would be good to upgrade it sooner rather than later.

• There are breaking changes in the v3 release. If we want to upgrade without making an Alloy v2 release, we should find a way to not incorporate breaking changes.
• I believe there have been changes to the remote write specification. We need to take special care that the prometheus.remote_write component works in a backwards compatible way.
• We need to incorporate new config arguments. For example an Alloy user noted that match_first_network in docker_sd_config would be useful.