[Feature] Add YANG Model for DEBUG_DROP_MONITOR

[arista-hpandya]

Description:

This issue tracks the creation and implementation of the YANG model required to support the persistent drop monitor feature in SONiC. This model will define the schema for DEBUG_DROP_MONITOR table.

Tasks:

• Define the YANG model structure for the persistent drop monitor configuration. This includes defining the following parameters:
  • Status (enabled/disabled toggle)
  • Window size (sliding time window in seconds)
  • Drop count threshold (minimum drops per window for an incident)
  • Incident count threshold (minimum incidents to trigger a syslog entry)
• Ensure the new YANG model is compatible with the existing CONFIG_DB schema and does not introduce conflicts.
• Write unit tests for the new YANG model.
• Update relevant documentation to reflect the new YANG model definition.

Background:

The persistent drop monitor feature allows for the configuration of thresholds to detect sustained drop patterns in SONiC drop counters. A corresponding YANG model is needed to represent these configurations in the CONFIG_DB, which acts as the communication channel between the CLI and orchagents. This YANG model will define the structure and validation rules for the configurable parameters.

References:

• Related HLD document: HLD document for configurable drop counter monitoring SONiC#1912
• Master issue tracking overall progress: Internal drop counter monitoring SONiC#1542