refactor: Making tritonclient.http and tritonclient.grpc health checks uniform

[KrishnanPrash]

This PR is meant to address a silent error not being caught in tritonclient.http.is_server_live() and tritonclient.http.is_server_ready().

Currently if we start a tritonserver instance with a health restricted feature specification, with the following command:

tritonserver --model-repo ... --grpc-restricted-protocol=health:health-key=health-value  --http-restricted-api=health:health-key=health-value

Then if we use tritonclient to query for health information, we receive the following:

>>> import tritonclient.http as httpclient
>>> import tritonclient.grpc as grpcclient
>>> http_client = httpclient.InferenceServerClient("localhost:8000")
>>> grpc_client = grpcclient.InferenceServerClient("localhost:8001")
>>> grpc_client.is_server_ready(headers={"triton-grpc-protocol-health-key":"health-value"})
True
>>> http_client.is_server_ready(headers={"health-key":"health-value"})
True
>>> grpc_client.is_server_ready(headers={"invalid-key":"invalid-value"})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.10/dist-packages/tritonclient/grpc/_client.py", line 344, in is_server_ready
    raise_error_grpc(rpc_error)
  File "/usr/local/lib/python3.10/dist-packages/tritonclient/grpc/_utils.py", line 77, in raise_error_grpc
    raise get_error_grpc(rpc_error) from None
tritonclient.utils.InferenceServerException: [StatusCode.UNAVAILABLE] This protocol is restricted, expecting header 'triton-grpc-protocol-health-key'
>>> http_client.is_server_ready(headers={"invalid-key":"invalid-value"}) # Should be erroring out with InferenceServerException: This API is restricted, expecting header 'health-key`
False 

From the above example, we can see that tritonclient provides different behavior for grpc and http in terms of erroring out when invalid credentials are presented.