ceph: match live blank-line separators between mds sections

Diffing the render against the live /etc/ceph/ceph.conf on prodnxsr0009
showed the hand-maintained file separates the mds sections with blank
lines: one before [mds] and one before each [mds.X-i] block (no trailing
blank line after the last). Emit those separators so a mon/mgr/mds host
renders byte-identical to live except for the intended public_network
normalization. Verified: osd host stays byte-identical, mon host differs
only on the public_network line.

Claude-Session: https://claude.ai/code/session_01JUoARVdmhxKQHyyyp1pxeT

site/profiles/templates/ceph/client.conf.erb

@@ -14,11 +14,13 @@
   osd_pool_default_pg_num = <%= @osd_pool_default_pg_num %>
   public_network = <%= @cluster_public_ips.map { |ip| "#{ip}/32" }.join(',') %>
 <% if @render_mds_config -%>
+
 [mds]
   keyring = <%= @mds_common['keyring'] %>
   mds_standby_replay = <%= @mds_common['mds_standby_replay'] %>
 <% @mds_instances.sort.each do |host, count| -%>
 <% (1..count).each do |instance| -%>
+
 [mds.<%= host %>-<%= instance %>]
   host = <%= host %>
 <% end -%>