kayobe seed host configure fails to start docker service in seed vm running Rocky 9.3 image

[Adam McCartney]

**Bug Report**

Running `kayobe seed vm provision` fails to start the docker service in the seed vm.
The error can be seen in the following handler:

```
RUNNING HANDLER [openstack.kolla.docker : Restart docker] ************************************************************************
fatal: [seed]: FAILED! => {"changed": false, "msg": "Unable to start service docker: Job for docker.service failed because the control process exited with error code.\nSee \"systemctl status docker.service\" and \"journalctl -xeu docker.service\" for details.\n"}
```

The journalctl logs provide a bit more info:

```
May 17 10:02:33 seed dockerd[28976]: unable to configure the Docker daemon with file /etc/docker/daemon.json: json: cannot unmarshal string into Go struct field Config.>
May 17 10:02:33 seed systemd[1]: docker.service: Main process exited, code=exited, status=1/FAILURE
```

The failure is due to a type error when parsing `/etc/docker/daemon.json`, line 19 shows that "mtu" is set to a string value.

**Fix**

Add a type in the ansible role for docker:

```
diff --git a/ansible/roles/docker/tasks/main.yml b/ansible/roles/docker/tasks/main.yml
index 13fd6bd0..1ee5976e 100644
--- a/ansible/roles/docker/tasks/main.yml
+++ b/ansible/roles/docker/tasks/main.yml
@@ -11,7 +11,7 @@
       {%- set _ = options.update({"registry-mirrors": docker_registry_mirrors}) -%}
       {%- endif -%}
       {%- if docker_daemon_mtu -%}
- {%- set _ = options.update({"mtu": docker_daemon_mtu}) -%}
+ {%- set _ = options.update({"mtu": docker_daemon_mtu | int}) -%}
       {%- endif -%}
       {%- if docker_daemon_live_restore | bool -%}
       {%- set _ = options.update({"live-restore": docker_daemon_live_restore | bool}) -%}
```

After applying this patch, the `kayobe seed vm provision` playbook succeeds and the docker service is started in the seed vm.

**Environment**

* OS: Rocky Linux 9.3 (Blue Onyx)

* Kernel: Linux seed 5.14.0-362.8.1.el9_3.x86_64

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/kayobe/+/919427
Committed: https://opendev.org/openstack/kayobe/commit/2e7b5287f39e27fe9c0ba4dcec4ffb355853a468
Submitter: "Zuul (22348)"
Branch: master

commit 2e7b5287f39e27fe9c0ba4dcec4ffb355853a468
Author: Adam McCartney <email address hidden>
Date: Fri May 17 13:49:38 2024 +0200

    Add type for mtu field in docker role

    Closes-Bug: #2066032

    This patch adds an integer type to the task in the docker role that
    generates the docker daemon config. This was previously uncast and
    defaulting to a string type, which causes an error with certain docker
    versions (via the Rocky 9.3 distro). See bug description for more info.

    Change-Id: I2a996fa22fedece2c894b378fadbfc5dd0c045b6