[confighttp] Use configoptional.Optional for CookiesConfig (#14154)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

<!-- Issue number if applicable -->

Uses `configoptional.Optional` for `confighttp.ClientConfig.Cookies`
field.

This should be transparent for end users iff they have the
`configoptional.AddEnabledField` feature gate enabled (the default)

#### Link to tracking issue
Updates #14021

Author: mx-psi

.chloggen/mx-psi_cookies-config-use-configoptional.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: pkg/config/confighttp
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Use configoptional.Optional for confighttp.ClientConfig.Cookies field
+
+# One or more tracking issues or pull requests related to the change
+issues: [14021]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

config/confighttp/client.go

@@ -101,7 +101,7 @@ type ClientConfig struct {
 	// If not set or set to 0, it defaults to 15s.
 	HTTP2PingTimeout time.Duration `mapstructure:"http2_ping_timeout,omitempty"`
 	// Cookies configures the cookie management of the HTTP client.
-	Cookies CookiesConfig `mapstructure:"cookies,omitempty"`
+	Cookies configoptional.Optional[CookiesConfig] `mapstructure:"cookies,omitempty"`
 
 	// Enabling ForceAttemptHTTP2 forces the HTTP transport to use the HTTP/2 protocol.
 	// By default, this is set to true.
@@ -116,9 +116,7 @@ type ClientConfig struct {
 
 // CookiesConfig defines the configuration of the HTTP client regarding cookies served by the server.
 type CookiesConfig struct {
-	// Enabled if true, cookies from HTTP responses will be reused in further HTTP requests with the same server.
-	Enabled bool `mapstructure:"enabled,omitempty"`
-	_       struct{}
+	_ struct{}
 }
 
 // NewDefaultClientConfig returns ClientConfig type object with
@@ -265,7 +263,7 @@ func (cc *ClientConfig) ToClient(ctx context.Context, host component.Host, setti
 	}
 
 	var jar http.CookieJar
-	if cc.Cookies.Enabled {
+	if cc.Cookies.HasValue() {
 		jar, err = cookiejar.New(&cookiejar.Options{PublicSuffixList: publicsuffix.List})
 		if err != nil {
 			return nil, err

config/confighttp/client_test.go

@@ -75,7 +75,7 @@ func TestAllHTTPClientSettings(t *testing.T) {
 				IdleConnTimeout:      idleConnTimeout,
 				Compression:          "",
 				DisableKeepAlives:    true,
-				Cookies:              CookiesConfig{Enabled: true},
+				Cookies:              configoptional.Some(CookiesConfig{}),
 				HTTP2ReadIdleTimeout: idleConnTimeout,
 				HTTP2PingTimeout:     http2PingTimeout,
 			},
@@ -97,7 +97,7 @@ func TestAllHTTPClientSettings(t *testing.T) {
 				IdleConnTimeout:      idleConnTimeout,
 				Compression:          "",
 				DisableKeepAlives:    true,
-				Cookies:              CookiesConfig{Enabled: true},
+				Cookies:              configoptional.Some(CookiesConfig{}),
 				HTTP2ReadIdleTimeout: idleConnTimeout,
 				HTTP2PingTimeout:     http2PingTimeout,
 			},