Currently, we configure LimitNOFILE on scylla-server.service, but we don't configure fs.nr_open and fs.file-max. When fs.nr_open or fs.file-max are smaller than LimitNOFILE, we may fail to allocate FDs. To fix this issue, raise fs.file-max and fs.nr_open to enogh size for scylla. Fixes #9461 Closes #9461