debian/control: Add libxsimd-dev build dependency for vendored Arrow

debian/control: Add libxsimd-dev build dependency for vendored Arrow

In commit e8460cbd, we introduced the "pkg.ceph.arrow" build profile to
support building with system Arrow packages. However, neither Debian nor
Ubuntu currently ships Arrow packages.

Since WITH_RADOSGW_SELECT_PARQUET is always enabled in debian/rules,
Arrow support is required for all builds. When the pkg.ceph.arrow profile
is not selected, the build uses vendored Arrow. With the recent change to
use AUTO mode for xsimd detection, Arrow will attempt to find system xsimd
>= 9.0.1. Adding libxsimd-dev as a build dependency ensures it's available
for Arrow to detect and use, reducing build time on supported distributions.

On distributions with insufficient xsimd versions (< 9.0.1), Arrow will
automatically fall back to its bundled version.

Signed-off-by: Kefu Chai <k.chai@proxmox.com>