dashboard: show ten of the current top receiver

dashboard: show ten of the current top receiver

not only five, as with the higher panels we already got enough space,
as one row needs roughly 24 px, lower top/bottom padding a bit to get
~242 of space, fitting ten entries nicely.

The performance aspect should not matter much, getting five or ten
entries from a DB like PostgreSQL is really not costing much,
especially as with the count query in use the hard work has already
been done anyway.

Makes the top-receiver panel look a bit more coherent compared to the
node info one beside it.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>