Add support for metric to track the maximum number of devices permitted to connect to a Talaria instance.

[ChaitanyaSingla]

We need to introduce a metric in Talaria that reflects the maximum number of devices permitted to connect to a Talaria instance. This pull request includes the addition of a metric to monitor the maximum allowed device connections for Talaria.

Reference issue for this MR: #299

cc: @Sachin4403

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