units: unify deps between service and socket units

The current arrangement of service and socket units is
sort of all over the place. Let's clean it up a little,
roughly following the principles below:

- socket units have implicit ordering deps (not to be confused
  with default ones which are subject to DefaultDependencies=)
  before associated service, so drop any explicit After=

- If socket can be enabled, remember to link to it in service
  via Also= and Sockets= (the latter replaces Wants=).
  If the service Requires= socket however, Sockets= is omitted.

- If socket is statically enabled, no need for service
  to pull it in - machined

units/systemd-importd.service.in

@@ -12,7 +12,6 @@ Description=Disk Image Download Service
 Documentation=man:systemd-importd.service(8)
 Documentation=man:org.freedesktop.import1(5)
 DefaultDependencies=no
-After=systemd-importd.socket
 WantsMountsFor=/var/lib/machines /var/lib/portables /var/lib/extensions /var/lib/confexts
 After=systemd-remount-fs.service
 Before=shutdown.target

units/systemd-machined.service.in

@@ -12,8 +12,8 @@ Description=Virtual Machine and Container Registration Service
 Documentation=man:systemd-machined.service(8)
 Documentation=man:org.freedesktop.machine1(5)
 
-Wants=machine.slice systemd-machined.socket
-After=machine.slice systemd-machined.socket
+Wants=machine.slice
+After=machine.slice
 RequiresMountsFor=/var/lib/machines
 
 [Service]

units/systemd-mountfsd.service.in

@@ -12,7 +12,7 @@ Description=DDI File System Mounter
 Documentation=man:systemd-mountfsd.service(8)
 Wants=modprobe@loop.service modprobe@dm_mod.service
 Requires=systemd-mountfsd.socket
-After=systemd-mountfsd.socket modprobe@loop.service modprobe@dm_mod.service
+After=modprobe@loop.service modprobe@dm_mod.service
 Conflicts=shutdown.target
 Before=sysinit.target shutdown.target
 DefaultDependencies=no

units/systemd-networkd.service.in

@@ -14,10 +14,10 @@ Documentation=man:org.freedesktop.network1(5)
 ConditionCapability=CAP_NET_ADMIN
 DefaultDependencies=no
 # systemd-udevd.service can be dropped once tuntap is moved to netlink
-After=systemd-networkd.socket systemd-udevd.service network-pre.target systemd-sysusers.service systemd-sysctl.service
+After=systemd-udevd.service network-pre.target systemd-sysusers.service systemd-sysctl.service
 Before=network.target multi-user.target shutdown.target initrd-switch-root.target
 Conflicts=shutdown.target initrd-switch-root.target
-Wants=systemd-networkd.socket network.target systemd-networkd-persistent-storage.service
+Wants=network.target systemd-networkd-persistent-storage.service
 
 [Service]
 AmbientCapabilities=CAP_NET_ADMIN CAP_NET_BIND_SERVICE CAP_NET_BROADCAST CAP_NET_RAW CAP_BPF CAP_SYS_ADMIN
@@ -46,6 +46,7 @@ RestrictRealtime=yes
 RestrictSUIDSGID=yes
 RuntimeDirectory=systemd/netif
 RuntimeDirectoryPreserve=yes
+Sockets=systemd-networkd.socket
 SystemCallArchitectures=native
 SystemCallErrorNumber=EPERM
 SystemCallFilter=@system-service bpf

units/systemd-nsresourced.service.in

@@ -11,7 +11,6 @@
 Description=Namespace Resource Manager
 Documentation=man:systemd-nsresourced.service(8)
 Requires=systemd-nsresourced.socket
-After=systemd-nsresourced.socket
 Conflicts=shutdown.target
 Before=sysinit.target shutdown.target
 DefaultDependencies=no

units/systemd-oomd.service.in

@@ -20,7 +20,7 @@ ConditionPathExists=/proc/pressure/cpu
 ConditionPathExists=/proc/pressure/io
 ConditionPathExists=/proc/pressure/memory
 Requires=systemd-oomd.socket
-After=systemd-oomd.socket systemd-sysusers.service
+After=systemd-sysusers.service
 
 [Service]
 AmbientCapabilities=CAP_KILL CAP_DAC_OVERRIDE
@@ -60,3 +60,4 @@ User=systemd-oom
 [Install]
 WantedBy=multi-user.target
 Alias=dbus-org.freedesktop.oom1.service
+Also=systemd-oomd.socket

units/systemd-resolved.service.in

@@ -15,10 +15,10 @@ Documentation=https://systemd.io/WRITING_NETWORK_CONFIGURATION_MANAGERS
 Documentation=https://systemd.io/WRITING_RESOLVER_CLIENTS
 
 DefaultDependencies=no
-After=systemd-sysctl.service systemd-sysusers.service systemd-resolved-varlink.socket systemd-resolved-monitor.socket
+After=systemd-sysctl.service systemd-sysusers.service
 Before=sysinit.target network.target nss-lookup.target shutdown.target initrd-switch-root.target
 Conflicts=shutdown.target initrd-switch-root.target
-Wants=nss-lookup.target systemd-resolved-varlink.socket systemd-resolved-monitor.socket
+Wants=nss-lookup.target
 
 [Service]
 AmbientCapabilities=CAP_SETPCAP CAP_NET_RAW CAP_NET_BIND_SERVICE
@@ -45,6 +45,7 @@ RestrictRealtime=yes
 RestrictSUIDSGID=yes
 RuntimeDirectory=systemd/resolve
 RuntimeDirectoryPreserve=yes
+Sockets=systemd-resolved-varlink.socket systemd-resolved-monitor.socket
 SystemCallArchitectures=native
 SystemCallErrorNumber=EPERM
 SystemCallFilter=@system-service

units/systemd-userdbd.service.in

@@ -11,7 +11,6 @@
 Description=User Database Manager
 Documentation=man:systemd-userdbd.service(8)
 Requires=systemd-userdbd.socket
-After=systemd-userdbd.socket
 Before=sysinit.target
 Wants=systemd-userdb-load-credentials.service
 DefaultDependencies=no