Bug 2008308 - fix(rust): ignore core::result::unwrap_failed (#7115)

Author: ErichDonGubler

socorro/signature/siglists/irrelevant_signature_re.txt

@@ -35,6 +35,7 @@ core::panicking::
 core::ptr::write
 core::ptr::mut_ptr
 core::result::impl\$
+core::result::unwrap_failed
 core::result::Result<T>
 core::slice::index
 core::sync::atomic::