MM-14686 Send all image proxy requests through /api/v4/image (#10775)

* MM-14686 Implement /api/v4/image when proxy is disabled

* MM-14686 Send all image proxy requests through /api/v4/image

* Update unit tests

services/imageproxy/local.go

@@ -10,7 +10,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
-	"strings"
 	"time"
 
 	"github.com/mattermost/mattermost-server/mlog"
@@ -105,33 +104,3 @@ func (backend *LocalBackend) GetImageDirect(imageURL string) (io.ReadCloser, str
 
 	return ioutil.NopCloser(recorder.Body), recorder.Header().Get("Content-Type"), nil
 }
-
-func (backend *LocalBackend) GetProxiedImageURL(imageURL string) string {
-	siteURL := *backend.proxy.ConfigService.Config().ServiceSettings.SiteURL
-
-	if imageURL == "" || imageURL[0] == '/' || strings.HasPrefix(imageURL, siteURL) {
-		return imageURL
-	}
-
-	return siteURL + "/api/v4/image?url=" + url.QueryEscape(imageURL)
-}
-
-func (backend *LocalBackend) GetUnproxiedImageURL(proxiedURL string) string {
-	siteURL := *backend.proxy.ConfigService.Config().ServiceSettings.SiteURL
-
-	if !strings.HasPrefix(proxiedURL, siteURL+"/api/v4/image?url=") {
-		return proxiedURL
-	}
-
-	parsed, err := url.Parse(proxiedURL)
-	if err != nil {
-		return proxiedURL
-	}
-
-	u := parsed.Query()["url"]
-	if len(u) == 0 {
-		return proxiedURL
-	}
-
-	return u[0]
-}