Remove docker from the provision OperatingSystemConfig

[Kostov6]

How to categorize this PR?

/area os
/kind cleanup
/os garden-linux

What this PR does / why we need it:
This PR removes executions of docker commands in the init OperatingSystemConfig.

From Gardener side, the docker binary is no longer used/required on a Shoot Node: gardener/gardener#4673.
From gardeninux OS side, [email protected]+ no longer includes the docker binary unit in the OS.

Which issue(s) this PR fixes:
N/A

Special notes for your reviewer:
N/A

Release note:

The os-gardenlinux extension does no longer enable and restart the `docker` unit as part of the init OperatingSystemConfig. Gardener and Kubernetes does no longer support `docker` as CRI. Gardener does no longer rely on the `docker` binary to be present on the Nodes. [[email protected]+](https://github.com/gardenlinux/gardenlinux/releases/tag/1443.1) no longer includes the `docker` binary unit in the OS.

The os-gardenlinux extension does no longer enable and restart the `docker` unit as part of the init OperatingSystemConfig. If you, as end user, rely on the docker unit to be enabled by default on the Node, this is a breaking change for you. In such case, you would need to enable the docker unit on your own.
Pay attention that [[email protected]+](https://github.com/gardenlinux/gardenlinux/releases/tag/1443.1) no longer includes the `docker` binary unit in the OS.

[ialidzhikov]

/lgtm

[ialidzhikov]

We had a sync with @vpnachev and @Kostov6 to discuss if such change might be a breaking one for end users that make use of the docker binary/unit on the Node outside of Kubernetes (not recommended). The breaking change would be end user to rely on the docker unit to be enabled for gardenlinux versions that still contain the unit/binary.

To be on the safe side, we decided to hold with the change until end of February when old gardenlinux version which still contain docker such as [email protected] and [email protected] reach EoL.

/hold