Remove deprecated compute config options for validation-2

Below compute config options for validation server had been
deprecated with corresponding options in validation group almost
year back.
- 1908e37d2551760831e338788511db93d5129e16

    - ``compute.image_ssh_user`` (available as ``validation.image_ssh_user``)
    - ``compute.ssh_user`` (available as ``validation.image_ssh_user``)
    - ``scenario.ssh_user`` (available as ``validation.image_ssh_user``)
    - ``compute.network_for_ssh`` (available as ``validation.network_for_ssh``)
    - ``compute.ping_timeout `` (available as ``validation.ping_timeout``)

This patch removes them from tempest conf.

Few plugins still using the old configs and this depends on their fix.

Change-Id: I2221b2d50fee97a464c7d5f0b3c2e13142cb394f
2 files changed