[MM-52445] Fix double url encoding of oauth redirect URI params (#23176)

* [MM-52445] Fix double url encoding of oauth redirect URI params

* Additional test based on code review

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/oauth.go

@@ -178,8 +178,8 @@ func (a *App) GetOAuthCodeRedirect(userID string, authRequest *model.AuthorizeRe
 		uri.RawQuery = queryParams.Encode()
 		return uri.String(), nil
 	}
-	queryParams.Set("code", url.QueryEscape(authData.Code))
-	queryParams.Set("state", url.QueryEscape(authData.State))
+	queryParams.Set("code", authData.Code)
+	queryParams.Set("state", authData.State)
 	uri.RawQuery = queryParams.Encode()
 	return uri.String(), nil
 }