Update the signing cert on the azure KV

Signed-off-by: Sayan Chowdhury <sayan.chowdhury2012@gmail.com>

Author: sayanchowdhury

build_library/sbsign_util.sh

@@ -6,7 +6,7 @@ if [[ ${COREOS_OFFICIAL:-0} -ne 1 ]]; then
     SBSIGN_KEY="/usr/share/sb_keys/shim.key"
     SBSIGN_CERT="/usr/share/sb_keys/shim.pem"
 else
-    SBSIGN_KEY="pkcs11:token=flatcar-sb-dev-hsm-sign-2025"
+    SBSIGN_KEY="pkcs11:token=flatcar-secure-boot-prod-2026-04"
     unset SBSIGN_CERT
 fi