You are passing the pipeline value Advisor Pipeline, but that is the label of your pipeline, not its pipelineId. Pass default instead. This internal value can be viewed in Settings > Sales > Deals > Advisor Pipeline > </> and with the CRM Pipelines API.
Similarly, you are passing the dealstage value New Enquiry, but that is also the label of the deal stage, not its stageId. Use appointmentscheduled instead. These internal values can be viewed in Settings > Sales > Deals > Advisor Pipeline > New Enquiry > </> and with the CRM Pipelines API.
After making these two changes, I was able to successfully create this test deal in your account.
INFO 2020-03-24 20:45:22,394 [SimpleAsyncTaskExecutor-2] com.bfa.serviceimpl.hubspot.HubSpotService - Printing the hubspot base URL :https://api.hubapi.com/deals/v1/deal?hapikey=axy
INFO 2020-03-24 20:45:22,395 [SimpleAsyncTaskExecutor-2] com.bfa.serviceimpl.hubspot.HubSpotService - Printing the request body :{"associations":{"associatedVids":[4951],"additionalProperties":{}},"properties":[{"name":"lp_coverage_duration","value":"Till Age 65"},{"name":"lp_coverage_amount","value":"400000.0"},{"name":"lp_premium_waiver","value":"false"},{"name":"dealstage","value":"New Enquiry"},{"name":"pipeline","value":"Advisor Pipeline"},{"name":"plan_type","value":"TM Term Assure II"},{"name":"dealname","value":"Coverage Duration:Till Age 65|Coverage Amount:400000.0|Premium Waiver:false"}]}
Making a POST request : https://api.hubapi.com/deals/v1/deal?hapikey=abc
Printing the hubspot deal response:<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<title>Error 400 Bad Request</title>
</head>
<body><h2>HTTP ERROR 400</h2>
<p>Problem accessing /deals/v1/deal. Reason:
<pre> Bad Request</pre></p>
</body>
</html>