Merged PR 58137: Get only the first IP for consent if request is forw…

…arded

## What's being changed

When we get the user's IP address for storing against their consent record, we are now fetching only the first listed IP address.

## Why it's being changed

API v3 now returns an error like:
```
"String '<redacted-actual-client-ip>, 127.0.0.1' does not validate against format 'ipv4'. Path: 'consentRecords[0].ipAddress'."
```

IPs can be formed like this if the request is forwarded by a load balancer or proxy server.

## How to review / test this change

- Lorem
- ipsum

## Notes

We manipulate the IP address elsewhere already - see `Model\Integration\IntegrationSetup::getEcSignupUrl()`. I didn't DRY this up for the time being, opting for a quick fix.

Related work items: #271210

Model/Consent/ConsentManager.php

@@ -217,7 +217,12 @@ private function isLinkMatchCustomerRegistrationOrCheckout(string $consentUrl):
      */
     private function getClientIp()
     {
-        return $this->http->getClientIp();
+        $clientIp = $this->http->getClientIp();
+        if (strpos($clientIp, ',') !== false) {
+            $ipList = explode(',', $clientIp);
+            $clientIp = trim(reset($ipList));
+        }
+        return $clientIp;
     }
 
     /**