update comments about globus_user and _pass in host_vars template files

[SebastienGardoll]

Describe the bug

Comments in the host_vars templates like myhost.my.org.yml, specifies that the globus_user and globus_pass variables are not mandatories. But upgrading to the version 4.0.4 fails when these variables are missing.

Globus Services

This information is used to connect the node
to the Globus system. Note globus_user should
not include the "@globusid.org" portion.

Leave unspecified and the Globus Connect Server
setup steps will be skipped.

#globus_user:
#globus_pass:

To Reproduce
Steps to reproduce the behavior:

1. Upgrade a node to the version 4.0.4
2. See error

ESGF Node (please complete the following information):

• Managed OS: CentOS 6
• Host OS: CentOS 7
• esgf-ansible Version: 4.0.4
• Node type: all