feat: set default log level to INFO

[C8Y-Mario]

Set the default log level to INFO for all logger instances
Add a new "loglevel" setting in base config that will be respected by the logger instances

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
15	0	0	15	100	0s

Passed Tests

Name	⏱️ Duration	Suite
Device should support the operation c8y_ModbusConfiguration	0.000 s	Device
Set values via c8y_ModbusConfiguration Operation	0.000 s	Operation
Poll rate and transmit rate should be updated for the Device	0.000 s	Operation
Poll rate and transmit rate should be updated on the Device	0.000 s	Operation
Device should support the operation c8y_ModbusDevice	0.000 s	Device
Device should have installed software tedge-modbus-plugin	0.000 s	Debian
Service should be active	0.000 s	Debian
ReInstall Modbus Plugin	0.000 s	Debian
Device should have the fragment c8y_ModbusConfiguration	0.000 s	Device
ChildDevice TestCase1 should be created	0.000 s	Device
ChildDevice TestCase1 should have the fragment c8y_ModbusDevice	0.000 s	Device
Service tedge-modbus-plugin should be enabled	0.000 s	Device
ChildDevice TestCase1 should have a Test.Int16 Measurement	0.000 s	Telemetry
ChildDevice TestCase1 should have a Test.Float32 Measurement	0.000 s	Telemetry
ChildDevice TestCase1 should have Alarms of type TestAlarm on Coil Value 1	0.000 s	Telemetry

[reubenmiller]

Approved. I pushed the required formatting changes and had to rebase the PR after pushing some PRs to update the github Runner image used to run the system tests.