chore: Update OracleDB Mixin to use modern libraries & cleanup

[schmikei]

NOTE: all the wait time metrics when Alloy updated in v1.9.0 have changed from gauges => counter, we have made the signals reflect that

This PR updates the OracleDB mixin to use more modern tooling like the logs-lib, common-lib, signals API to make this mixin easier to maintain/extend.

User Impacts:

• Logs no longer exist on the OracleDB Overview Dashboard and now are their own dashboard logs.json
• Some updates to queries to better reflect the metrics being gathered by Grafana Alloy after v1.9.0, for the snippets of metrics please refer to https://github.com/oracle/oracle-db-appdev-monitoring?tab=readme-ov-file#standard-metrics as those are shipped by default for Grafana Alloy
• Placed top 3 panels of OracleDB dashboard within a row called Overview

Integration Docs: https://grafana.com/docs/grafana-cloud/monitor-infrastructure/integrations/integration-reference/integration-oracledb