fix(azure): fix credential caching key mismatch in driver storageAccountsClient

Similar to the azureclient fix, use consistent azureCredentialsKey for both
storing and loading cached credentials instead of mixing azureCredentialsKey
and userAssignedIdentityCredentialsFilePath. This prevents repeated credential
recreation in the Azure driver's storageAccountsClient method.

Author: bryan-cox

pkg/storage/azure/azure.go

@@ -384,7 +384,7 @@ func (d *driver) storageAccountsClient(cfg *Azure, environment autorestazure.Env
 		var ok bool
 
 		// We need to only store the Azure credentials once and reuse them after that.
-		storedCreds, found := d.azureCredentials.Load(userAssignedIdentityCredentialsFilePath)
+		storedCreds, found := d.azureCredentials.Load(azureCredentialsKey)
 		if !found {
 			klog.V(2).Info("Using UserAssignedIdentityCredentials for Azure authentication for managed Azure HCP")
 			clientOptions := azcore.ClientOptions{