fix: Respect proxy env vars in common HTTP client (#149)

* Respect proxy env vars in common HTTP client

* Implement review comments, use default http transport

* Use tabs instead of spaces

Author: chrisob

sysdig/internal/client/common/client.go

@@ -28,10 +28,11 @@ func WithExtraHeaders(client SysdigCommonClient, extraHeaders map[string]string)
 
 func NewSysdigCommonClient(sysdigAPIToken string, url string, insecure bool) SysdigCommonClient {
 	client := retryablehttp.NewClient()
+	transport := http.DefaultTransport.(*http.Transport).Clone()
+	transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: insecure}
+
 	client.HTTPClient = &http.Client{
-		Transport: &http.Transport{
-			TLSClientConfig: &tls.Config{InsecureSkipVerify: insecure},
-		},
+		Transport: transport,
 	}
 
 	return &sysdigCommonClient{