[confighttp] Remove pointer in CookiesConfig field (open-telemetry#13116)

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

Removes pointer to `CookiesConfig` field. Since the struct already has
an `enabled` field, it is unnecessary for it to be a pointer.

This is a breaking change, contrib tests show that it does not affect
any contrib component, and it would be hard to do in two steps.

<!-- Issue number if applicable -->
#### Link to tracking issue
Updates open-telemetry#9478

Author: mx-psi

.chloggen/mx-psi_cookiesconfig.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: confighttp
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Remove pointer to field `cookies` in confighttp.ClientConfig"
+
+# One or more tracking issues or pull requests related to the change
+issues: [13116]
+
+# (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: [api]

config/confighttp/confighttp.go

@@ -116,7 +116,7 @@ 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 CookiesConfig `mapstructure:"cookies,omitempty"`
 
 	// Middlewares are used to add custom functionality to the HTTP client.
 	// Middleware handlers are called in the order they appear in this list,
@@ -273,7 +273,7 @@ func (hcs *ClientConfig) ToClient(ctx context.Context, host component.Host, sett
 	}
 
 	var jar http.CookieJar
-	if hcs.Cookies != nil && hcs.Cookies.Enabled {
+	if hcs.Cookies.Enabled {
 		jar, err = cookiejar.New(&cookiejar.Options{PublicSuffixList: publicsuffix.List})
 		if err != nil {
 			return nil, err

config/confighttp/confighttp_test.go

@@ -91,7 +91,7 @@ func TestAllHTTPClientSettings(t *testing.T) {
 				IdleConnTimeout:      idleConnTimeout,
 				Compression:          "",
 				DisableKeepAlives:    true,
-				Cookies:              &CookiesConfig{Enabled: true},
+				Cookies:              CookiesConfig{Enabled: true},
 				HTTP2ReadIdleTimeout: idleConnTimeout,
 				HTTP2PingTimeout:     http2PingTimeout,
 			},