fix!: remove the unused --yes flag from coder autoupdate (#30149)

`coder autoupdate` has registered `-y/--yes` since #10438 but never
prompts, so the flag did nothing.
This PR removes it.

**Breaking change:** `coder autoupdate` no longer accepts `-y/--yes`.
Scripts that pass it now fail with `unknown shorthand flag: 'y'`.
To fix them, drop the flag; it never had an effect.

<details>
<summary>Decisions</summary>

- The first version kept `-y` as a hidden no-op so existing scripts
wouldn't break.
- Reviewers preferred removing it outright as a breaking change, since a
deprecation period would end in the same removal and the hidden flag is
cruft.
- The title uses `fix!:` and the PR carries `release/breaking`, so the
release tooling lists it under breaking changes.
- `cliui.HiddenSkipPromptOption()` landed on `main` through the
organizations create PR and stays there for that command; this PR no
longer touches it.
- The test now pins the new behavior: passing `-y` returns an unknown
flag error.

</details>

Closes [CLI-33](https://linear.app/codercom/issue/CLI-33)

_This PR was generated by Coder Agents on behalf of @nickvigilante._

cli/autoupdate.go

@@ -6,7 +6,6 @@ import (
 
 	"golang.org/x/xerrors"
 
-	"github.com/coder/coder/v2/cli/cliui"
 	"github.com/coder/coder/v2/codersdk"
 	"github.com/coder/serpent"
 )
@@ -47,7 +46,6 @@ func (r *RootCmd) autoupdate() *serpent.Command {
 		},
 	}
 
-	cmd.Options = append(cmd.Options, cliui.SkipPromptOption())
 	return cmd
 }
 

cli/autoupdate_test.go

@@ -41,6 +41,14 @@ func TestAutoUpdate(t *testing.T) {
 		require.Equal(t, expectedPolicy, workspace.AutomaticUpdates)
 	})
 
+	t.Run("YesFlagRejected", func(t *testing.T) {
+		t.Parallel()
+
+		inv, _ := clitest.New(t, "autoupdate", "my-workspace", string(codersdk.AutomaticUpdatesAlways), "-y")
+		err := inv.Run()
+		require.ErrorContains(t, err, "unknown shorthand flag: 'y'")
+	})
+
 	t.Run("InvalidArgs", func(t *testing.T) {
 		type testcase struct {
 			Name          string

cli/testdata/coder_autoupdate_--help.golden

@@ -1,13 +1,9 @@
 coder v0.0.0-devel
 
 USAGE:
-  coder autoupdate [flags] <workspace> <always|never>
+  coder autoupdate <workspace> <always|never>
 
   Toggle auto-update policy for a workspace
 
-OPTIONS:
-  -y, --yes bool
-          Bypass confirmation prompts.
-
 ———
 Run `coder --help` for a list of global options.

docs/reference/cli/autoupdate.md

@@ -11,15 +11,5 @@ Toggle auto-update policy for a workspace
 ## Usage
 
 ```console
-coder autoupdate [flags] <workspace> <always|never>
+coder autoupdate <workspace> <always|never>
 ```
-
-## Options
-
-### -y, --yes
-
-|      |                   |
-|------|-------------------|
-| Type | <code>bool</code> |
-
-Bypass confirmation prompts.