Change proxy_url from url.URL to string (#28725)

(cherry picked from commit f025c96)

CHANGELOG.next.asciidoc

@@ -127,6 +127,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Fix handling of float data types within processors. {issue}28279[28279] {pull}28280[28280]
 - Allow `clone3` syscall in seccomp filters. {pull}28117[28117]
 - Remove unnecessary escaping step in dashboard loading, so they can be displayed in Kibana. {pull}28395[28395]
+- Fix AWS proxy_url config from url to string type.  {pull}28725[28725]
 - Fix `fingerprint` processor to give it access to the `@timestamp` field. {issue}28683[28683]
 
 *Auditbeat*

x-pack/libbeat/common/aws/credentials.go

@@ -15,28 +15,34 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/sts"
 	"github.com/pkg/errors"
 
+	"github.com/elastic/beats/v7/libbeat/common/transport/httpcommon"
 	"github.com/elastic/beats/v7/libbeat/logp"
 )
 
 // ConfigAWS is a structure defined for AWS credentials
 type ConfigAWS struct {
-	AccessKeyID          string   `config:"access_key_id"`
-	SecretAccessKey      string   `config:"secret_access_key"`
-	SessionToken         string   `config:"session_token"`
-	ProfileName          string   `config:"credential_profile_name"`
-	SharedCredentialFile string   `config:"shared_credential_file"`
-	Endpoint             string   `config:"endpoint"`
-	RoleArn              string   `config:"role_arn"`
-	ProxyUrl             *url.URL `config:"proxy_url"`
+	AccessKeyID          string `config:"access_key_id"`
+	SecretAccessKey      string `config:"secret_access_key"`
+	SessionToken         string `config:"session_token"`
+	ProfileName          string `config:"credential_profile_name"`
+	SharedCredentialFile string `config:"shared_credential_file"`
+	Endpoint             string `config:"endpoint"`
+	RoleArn              string `config:"role_arn"`
+	ProxyUrl             string `config:"proxy_url"`
 }
 
 // InitializeAWSConfig function creates the awssdk.Config object from the provided config
 func InitializeAWSConfig(config ConfigAWS) (awssdk.Config, error) {
 	AWSConfig, _ := GetAWSCredentials(config)
-	if config.ProxyUrl != nil {
+	if config.ProxyUrl != "" {
+		proxyUrl, err := httpcommon.NewProxyURIFromString(config.ProxyUrl)
+		if err != nil {
+			return AWSConfig, err
+		}
+
 		httpClient := &http.Client{
 			Transport: &http.Transport{
-				Proxy: http.ProxyURL(config.ProxyUrl),
+				Proxy: http.ProxyURL(proxyUrl.URI()),
 			},
 		}
 		AWSConfig.HTTPClient = httpClient