Consider renaming `system.network.dropped` to `system.network.packet.dropped`

[lmolkova]

See #1694 (comment)
It's not clear from the metric name what was dropped, would be great to clarify.

If it turns out that we'd like to keep system.network.dropped or rename it to something else, this issue should track updating naming guidelines.

[braydonk]

I agree with this! I was actually looking at my notes before the holidays and found this that I wrote before this issue had even opened:

`system.network.packets`, should the `dropped` and `packet` metrics be merged to be `system.network.packets` and `system.network.packets.dropped`?

Arguably this could even be system.network.packets.received so that the pattern matches system.network.packets.dropped. Does that sound reasonable?

Side note, I wonder if this (similar to other system.network namespace stuff) should simply be moved to network as well. For packets received and dropped, I don't feel the system namespace improves the understanding or organization of these metrics.

[mx-psi]

Discussed on the 2025-02-13. We agree on renaming to network.packet.received and network.packet.dropped because:

1. The namespace should be singular
2. The suffix received/dropped is more explicit as to what the metric means
3. These metrics could be used in containers as well so we don't think the system namespace is needed/correct

[rogercoll]

Arguably this could even be system.network.packets.received so that the pattern matches system.network.packets.dropped. Does that sound reasonable?

Note that the system.network.packets metric does not only refer to the "received" packets, but it uses the network.io.direction attribute to indicate the direction (received or transmit). My proposal would be using the system.network.io (similar to system.disk.io), which is already defined: https://github.com/open-telemetry/semantic-conventions/blob/main/docs/system/system-metrics.md#metric-systemnetworkio (duplicated metric? 🤔 ?

3. These metrics could be used in containers as well so we don't think the system namespace is needed/correct

Is this still valid of today? The decision taken in #2295 was to keep the system/container/kubernetes namespace to make it consistent with the other metrics (disk/network). Also, to denote area-wide metrics.

[mx-psi]

Is this still valid of today? The decision taken in #2295 was to keep the system/container/kubernetes namespace to make it consistent with the other metrics (disk/network). Also, to denote area-wide metrics.

I think it is not valid anymore