System metrics instrumentation looks for wrong config key for network instruments

[alexmojaki]

Describe your environment

opentelemetry-instrumentation-system-metrics==0.49b1

What happened?

The instruments system.network.packets and system.network.io are created if those strings are in the config, but the callbacks look for the wrong key system.network.dropped.packets.

Steps to Reproduce

This script configures each instrument in isolation to find errors like this.

from opentelemetry.instrumentation.system_metrics import (
    _DEFAULT_CONFIG,
    SystemMetricsInstrumentor,
)
from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import InMemoryMetricReader

for k, v in _DEFAULT_CONFIG.items():
    meter_provider = MeterProvider([InMemoryMetricReader()])
    instrumentor = SystemMetricsInstrumentor(config={k: v})
    instrumentor.instrument(meter_provider=meter_provider)
    meter_provider.force_flush()
    instrumentor.uninstrument()

Expected Result

No errors

Actual Result

Callback failed for instrument system.network.packets.
Traceback (most recent call last):
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/opentelemetry/sdk/metrics/_internal/instrument.py", line 136, in callback
    for api_measurement in callback(callback_options):
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/opentelemetry/instrumentation/system_metrics/__init__.py", line 598, in _get_system_network_packets
    for metric in self._config["system.network.dropped.packets"]:
                  ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 'system.network.dropped.packets'

Callback failed for instrument system.network.io.
Traceback (most recent call last):
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/opentelemetry/sdk/metrics/_internal/instrument.py", line 136, in callback
    for api_measurement in callback(callback_options):
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/opentelemetry/instrumentation/system_metrics/__init__.py", line 629, in _get_system_network_io
    for metric in self._config["system.network.dropped.packets"]:
                  ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: 'system.network.dropped.packets'

Additional context

In general the architecture here seems very prone to these kinds of copy-paste mistakes.

Would you like to implement a fix?

No

[xrmx]

Good catch, fun how we are supposed to have green tests asserting things