Deprecate BridgeNfIptables and BridgeNfIp6tables fields

The netfilter module is now loaded on-demand, and no longer during daemon
startup, making these fields obsolete. These fields are now always `false`
and will be removed in the next relase.

This patch deprecates:

- the `BridgeNfIptables` field in `api/types/system.Info`
- the `BridgeNfIp6tables` field in `api/types/system.Info`
- the `BridgeNFCallIPTablesDisabled` field in `pkg/sysinfo.SysInfo`
- the `BridgeNFCallIP6TablesDisabled` field in `pkg/sysinfo.SysInfo`

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/api/v1.47.yaml

@@ -5512,7 +5512,11 @@ definitions:
         type: "boolean"
         example: true
       BridgeNfIptables:
-        description: "Indicates if `bridge-nf-call-iptables` is available on the host."
+        description: |
+          Indicates if `bridge-nf-call-iptables` is available on the host when
+          the daemon was started.
+
+          The `br_netfilter`
         type: "boolean"
         example: true
       BridgeNfIp6tables:

docs/api/version-history.md

@@ -22,6 +22,10 @@ keywords: "API, Docker, rcli, REST, documentation"
   and `AllowNondistributableArtifactsHostnames` fields in the `RegistryConfig`
   struct in the `GET /info` response will now always be `null` and will be
   omitted in API v1.49.
+* Deprecated: The `BridgeNfIptables` and `BridgeNfIp6tables` fields in the 
+  `GET /info` response are now always be `false` and will be omitted in API
+  v1.49. The netfilter module is now loaded on-demand, and no longer during
+  daemon startup, making these fields obsolete.
 * `GET /images/{name}/history` now supports a `platform` parameter (JSON
   encoded OCI Platform type) that allows to specify a platform to show the
   history of.