chore: enable image for readOnlyRootFilesystem

with symlink to tmp for index.html

scripts/inject-dynamic-env.sh

@@ -23,4 +23,5 @@ custom_env_vars='{PORTAL_ASSETS_URL:"'$PORTAL_ASSETS_URL'",PORTAL_BACKEND_URL:"'
 custom_env_vars_anchor='{PORTAL_ASSETS_URL:"http://localhost:3000/assets",PORTAL_BACKEND_URL:"https://portal-backend.example.org",CENTRALIDP_URL:"https://centralidp.example.org/auth",BPDM_API_URL:"https://business-partners.example.org/pool/api",SEMANTICS_URL:"https://semantics.example.org",MANAGED_IDENTITY_WALLETS_NEW_URL:"https://managed-identity-wallets-new.example.org"}'
 index_html_reference=`cat /usr/share/nginx/html/index.html.reference`
 index_html=${index_html_reference//$custom_env_vars_anchor/$custom_env_vars}
-echo "$index_html" > /usr/share/nginx/html/index.html
+echo "$index_html" > /tmp/index.html
+ln -s /tmp/index.html /usr/share/nginx/html/index.html