docs: remove empty Azure DevOps Docker task (#25523)

### Description

Removes the empty `Docker@2` step from the Azure DevOps example in the
Docker Scout generic CLI integration guide. The following script already
passes the documented Docker Scout credentials into the Scout CLI
container, so the standalone task line has no inputs and would fail if
copied as-is.

Fixes #25084.

### Validation

- `git diff --check`
- `npx markdownlint-cli
content/manuals/scout/integrations/environment/cli.md`

`./scripts/lint.sh
content/manuals/scout/integrations/environment/cli.md` also ran
markdownlint clean, then stopped because `vale` is not installed in this
local environment.

Author: nielskaspers

content/manuals/scout/integrations/environment/cli.md

@@ -98,7 +98,6 @@ stages:
         pool:
           vmImage: ubuntu-latest
         steps:
-          - task: Docker@2
           - script: docker run -it \
               -e DOCKER_SCOUT_HUB_USER=$DOCKER_SCOUT_HUB_USER \
               -e DOCKER_SCOUT_HUB_PASSWORD=$DOCKER_SCOUT_HUB_PASSWORD \