fix: runtime load logo for footer

as you can see if logo is not falsy, the runtimevalue doesnt work.

https://github.com/openedx/frontend-component-footer/blob/master/src/components/Footer.jsx#L59

but gradebbok loaded with this value

https://github.com/openedx/frontend-app-gradebook/blob/open-release/palm.master/src/App.jsx#L30

.env

@@ -4,6 +4,7 @@ BASE_URL=''
 LMS_BASE_URL=''
 LOGIN_URL=''
 LOGOUT_URL=''
+LOGO_POWERED_BY_OPEN_EDX_URL_SVG=''
 CSRF_TOKEN_API_PATH=''
 REFRESH_ACCESS_TOKEN_ENDPOINT=''
 DATA_API_BASE_URL=''

.env.development

@@ -7,7 +7,7 @@ LOGOUT_URL='http://localhost:18000/login'
 LOGO_URL=https://edx-cdn.org/v3/default/logo.svg
 LOGO_TRADEMARK_URL=https://edx-cdn.org/v3/default/logo-trademark.svg
 LOGO_WHITE_URL=https://edx-cdn.org/v3/default/logo-white.svg
-LOGO_POWERED_BY_OPEN_EDX_URL_SVG=https://edx-cdn.org/v3/stage/open-edx-tag.svg
+LOGO_POWERED_BY_OPEN_EDX_URL_SVG=''
 FAVICON_URL=https://edx-cdn.org/v3/default/favicon.ico
 CSRF_TOKEN_API_PATH='/csrf/api/v1/token'
 REFRESH_ACCESS_TOKEN_ENDPOINT='http://localhost:18000/login_refresh'