chore: automatically set 'host-prefix-cookie' in https deployments (#22224)

The feature was never released, so this is not a breaking change

codersdk/deployment.go

@@ -2916,9 +2916,9 @@ func (c *DeploymentValues) Options() serpent.OptionSet {
 			Flag:        "host-prefix-cookie",
 			Env:         "CODER_HOST_PREFIX_COOKIE",
 			Value:       serpent.BoolOf(&c.HTTPCookies.EnableHostPrefix),
-			// Ideally this is true, however any frontend interactions with the coder api would be broken.
-			// So for compatibility reasons, this is set to false.
-			Default:     "false",
+			DefaultFn: func() string {
+				return strconv.FormatBool(c.AccessURL.Scheme == "https")
+			},
 			Group:       &deploymentGroupNetworking,
 			YAML:        "hostPrefixCookie",
 			Annotations: serpent.Annotations{}.Mark(annotationExternalProxies, "true"),

docs/reference/cli/server.md

@@ -1065,7 +1065,6 @@ Controls the 'SameSite' property is set on browser session cookies.
 | Type        | <code>bool</code>                        |
 | Environment | <code>$CODER_HOST_PREFIX_COOKIE</code>   |
 | YAML        | <code>networking.hostPrefixCookie</code> |
-| Default     | <code>false</code>                       |
 
 Recommended to be enabled. Enables `__Host-` prefix for cookies to guarantee they are only set by the right domain.