Adjust trial status progress from 0/30 → 1/30 for day one

What does this MR do and why?

• Changes display from 0/30 for first day to 1/30 as per #358038 (closed)
• Adds further test coverage for widget

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Setup GDK to simulate SaaS and restart - https://docs.gitlab.com/ee/development/ee_features.html#simulate-a-saas-instance
2. Set check namespace plan setting in rails console:

ApplicationSetting.first.update(check_namespace_plan: true)

3. Create a new top level Group
4. Setup the subscription in rails console:

g = Group.find 82 # this is the id of the group you just created
g.gitlab_subscription
gs = g.gitlab_subscription
gs.hosted_plan_id = 7 # this id will be the Plan id of the Ultimate Trial plan on your gdk
gs.trial = true
gs.trial_ends_on = 30.days.from_now
gs.trial_starts_on = Time.current
gs.save!

5. Goto the group's overview page and notice in the sidebar.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #358038 (closed)