Fix race condition in hostsetup.ps1.

There was a race condition in setting up credential port forwarding in which the adapter has multiple addresses before the new ip is assigned. Allowing this race condition can cause the netsh interface portproxy setup to result in the network adapter in an unrecoverable bad state where the proxy is unable to listen on port 80 because the port is in use by a non-functional proxy rule.

This race condition happened rarely before, but started becoming a problem when changes were made to let windows test run faster (aws#1886), which let TestV3TaskEndpointDefaultNetworkMode, TestV3TaskEndpointTags and TestV3TaskEndpointDefaultNetworkMode have a high failure rate because they need the credential port forwarding.

misc/windows-deploy/hostsetup.ps1

@@ -35,8 +35,39 @@ $dockerSubnet = (docker network inspect nat | ConvertFrom-Json).IPAM.Config.Subn
 $ip = (Get-NetRoute -InterfaceIndex $ifIndex -DestinationPrefix $dockerSubnet)
 if(!($ip)) {
 
+	$IPAddrParams = @{
+		InterfaceIndex = $ifIndex;
+		IPAddress = $credentialAddress;
+		PrefixLength = 32;
+	}
+
 	# This command tells the APIPA interface that this IP exists.
-	New-NetIPAddress -InterfaceIndex $ifIndex -IPAddress $credentialAddress -PrefixLength 32
+	New-NetIPAddress @IPAddrParams
+
+	[int]$delay = 1
+	[int]$maxTries = 10
+	[bool]$available = $false
+	while (-not $available -and $maxTries -ge 0) {
+		try {
+			$IPAddr = Get-NetIPAddress @IPAddrParams -ErrorAction:Ignore
+			if ($IPAddr) {
+				if ($($IPAddr.AddressState) -eq "Preferred") {
+					$available = $true
+					break;
+				} else {
+					Start-Sleep -Seconds $delay
+					$maxTries--
+				}
+			}
+		} catch {
+			# Prevent race condition where the adapter has multiple addresses before our new ip is assigned
+			# Note: Allowing this race condition can cause the netsh interface portproxy setup to result
+			#       in the network adapter in an unrecoverable bad state where the proxy is unable to
+			#       listen on port 80 because the port is in use by a non-functional proxy rule.
+			Start-Sleep -Seconds $delay
+			$maxTries--
+		}
+	}
 
 	# Enable the default docker IP range to be routable by the APIPA interface.
 	New-NetRoute -DestinationPrefix $dockerSubnet -ifIndex $ifindex