[arrow] Improve findzstd patch

[Neumann-A]

find_library call before:

ZSTD_LIBRARY_RELEASE;NAMES;zstd;zstd_staticd.lib;libzstd_staticd.lib;zstdd.dll;
ZSTD_LIBRARY_DEBUG;NAMES;zstdd;zstd_staticd.libd;libzstd_staticd.libd;zstdd.dlld;

after:

ZSTD_LIBRARY_RELEASE;NAMES;zstd;zstd_static;zstd;
ZSTD_LIBRARY_DEBUG;NAMES;zstdd;zstd_staticd;zstdd;

simplying removing the unnecessary extra library postfix.
(In the current state of VCPKG ZSTD_LIBRARY_DEBUG will never be found since zstd does not have an extra debug postfix. Maybe in the future)