Rremoved invalid metric from applicationGateways

Removed `BlockedReqCount` from `Microsoft.Network/applicationGateways` since is not supported
```bash
az monitor metrics list --resource /subscriptions/<subscription_id>/resourceGroups/<rg_name>/providers/Microsoft.Network/applicationGateways/<app_gw_name> --metric BlockedReqCount
(BadRequest) Failed to find metric configuration for provider: Microsoft.Network, resource Type: applicationGateways, metric: BlockedReqCount, Valid metrics: Throughput,UnhealthyHostCount,HealthyHostCount,TotalRequests,AvgRequestCountPerHealthyHost,FailedRequests,ResponseStatus,CurrentConnections,NewConnectionsPerSecond,CapacityUnits,FixedBillableCapacityUnits,EstimatedBilledCapacityUnits,ComputeUnits,BackendResponseStatus,TlsProtocol,BytesSent,BytesReceived,ClientRtt,ApplicationGatewayTotalTime,BackendConnectTime,BackendFirstByteResponseTime,BackendLastByteResponseTime,AzwafTotalRequests,AzwafCustomRule,AzwafSecRule,AzwafBotProtection
Code: BadRequest
Message: Failed to find metric configuration for provider: Microsoft.Network, resource Type: applicationGateways, metric: BlockedReqCount, Valid metrics: Throughput,UnhealthyHostCount,HealthyHostCount,TotalRequests,AvgRequestCountPerHealthyHost,FailedRequests,ResponseStatus,CurrentConnections,NewConnectionsPerSecond,CapacityUnits,FixedBillableCapacityUnits,EstimatedBilledCapacityUnits,ComputeUnits,BackendResponseStatus,TlsProtocol,BytesSent,BytesReceived,ClientRtt,ApplicationGatewayTotalTime,BackendConnectTime,BackendFirstByteResponseTime,BackendLastByteResponseTime,AzwafTotalRequests,AzwafCustomRule,AzwafSecRule,AzwafBotProtection
```

Author: maci3jka

articles/azure-monitor/essentials/metrics-supported.md

@@ -2496,7 +2496,6 @@ This latest update adds a new column and reorders the metrics to be alphabetical
 |BackendLastByteResponseTime|No|Backend Last Byte Response Time|MilliSeconds|Average|Time interval between start of establishing a connection to backend server and receiving the last byte of the response body|Listener, BackendServer, BackendPool, BackendHttpSetting|
 |BackendResponseStatus|Yes|Backend Response Status|Count|Total|The number of HTTP response codes generated by the backend members. This does not include any response codes generated by the Application Gateway.|BackendServer, BackendPool, BackendHttpSetting, HttpStatusGroup|
 |BlockedCount|Yes|Web Application Firewall Blocked Requests Rule Distribution|Count|Total|Web Application Firewall blocked requests rule distribution|RuleGroup, RuleId|
-|BlockedReqCount|Yes|Web Application Firewall Blocked Requests Count|Count|Total|Web Application Firewall blocked requests count|No Dimensions|
 |BytesReceived|Yes|Bytes Received|Bytes|Total|The total number of bytes received by the Application Gateway from the clients|Listener|
 |BytesSent|Yes|Bytes Sent|Bytes|Total|The total number of bytes sent by the Application Gateway to the clients|Listener|
 |CapacityUnits|No|Current Capacity Units|Count|Average|Capacity Units consumed|No Dimensions|