MT#60683 patch: Remove temporary import file

When we are done we should cleanup the temporary file to avoid leaving
cruft behind.

Change-Id: Ic5887d348862d12711207263c69a94c22e4bc0b4
(cherry picked from commit a3033c52c0)

scripts/patch

@@ -254,6 +254,7 @@ patch_import_customtt() {
     tail -n +3 "${tmp_patchtt}" > "${patchtt}"
   fi
 
+  rm -f "${tmp_patchtt}"
   rm -f "${diff_output}"
 }