Don't use default staging mountpoints on db1.staging

There is no swap partition used on this server so the /tmp tmpfs size computation is incorrect

Octocatalog diff:

diff origin/production/db1.internal.staging.swh.network current/db1.internal.staging.swh.network
*******************************************
- Exec[create /tmp]
*******************************************
- File[/tmp]
*******************************************
- Mount[/tmp]
*******************************************
- Mount[swap]
*******************************************
*** End octocatalog-diff on db1.internal.staging.swh.network