test: remove redundant 'file' command from gdb scripts.

test: remove redundant 'file' command from gdb scripts.

Quoting Debian bug 787341

   It failed to build on arm64: the last ten tests in T070-insert
   failed.

   What's happening here is that GDB is segfaulting in response to
   the
   "file" command. GDB on arm64 can be a bit buggy.

   However, the "file" command is redundant here as GDB has already
   got
   the file from the --args on the command line.