Changed `upgrade-charm` to alias `refresh`

[UtkarshBhatthere]

According to juju 2.9 docs, upgrade-charm is an alias for refresh and supports the required call in our life-cycle test. The same nomenclature is used by juju3 so switching to refresh syntax makes this juju version agnostic.

# juju version 
2.9.49-ubuntu-amd64

# juju refresh --help
Usage: juju refresh [options] <application>

Summary:
Refresh an application's charm.
...
--path (= "")
    Refresh to a charm located at path
...
Aliases: upgrade-charm

utkarsh@workbook:~$ juju version
3.5.1-genericlinux-amd64

utkarsh@workbook:~$ juju refresh --help
Usage: juju refresh [options] <application>

Summary:
Refresh an application's charm.
...
--path (= "")
    Refresh to a charm located at path
...

[UtkarshBhatthere]

Can someone trigger the failed tests again ? I am seeing: Applications in error state: ntp

[ajkavanagh]

Can someone trigger the failed tests again ? I am seeing: Applications in error state: ntp

I've re-triggered the failed jobs; let's see what happens.