[lldb] Remove stale LLDB-Info.plist

Remove the stale LLDB-Info.plist which was only used by TestHelp.py. The
latter would try to parse the version number from the plist and use that
to verify the version in the help output. Of course this never matched
so it would fall back to matching any arbitrary version.

This patch does *not* change the real LLDB-Info.plist.in file which is
used for the LLDB Framework.