feat(fwu): add a case to corrupt FWU-metadata

Add a case within the 'corrupt_gpt_bin' function specifically
tailored for corrupting FWU metadata. This case should be
adaptable for use in a test configuration aimed at
corrupting FWU metadata.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I18ff6abd2499bcdb1a32f88bc15f89c1fdd5efa0
diff --git a/expect/backup_fwu_metadata.exp b/expect/backup_fwu_metadata.exp
new file mode 100644
index 0000000..f18b616
--- /dev/null
+++ b/expect/backup_fwu_metadata.exp
@@ -0,0 +1,15 @@
+#
+# Copyright (c) 2024 Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# Expect script for Trusted Firmware Test Framework
+#
+
+source [file join [file dirname [info script]] handle-arguments.inc]
+
+expect_string "loading of FWU-Metadata failed, using Bkup-FWU-Metadata"
+
+source [file join [file dirname [info script]] tftf.inc]
+
+exit_uart -1