Make storage adjustment a little nicer, especially the first time

Summary:
Fixes T11583.

• When users run bin/storage upgrade for the first time on a new install, we currently give them a prompt which feels rough and which they can only reasonably ever answer "yes" to.
• We generally use cautionary language ("found issues with schema") in this workflow. Adjustments are now routine, so use more neutral and progress-oriented language ("found adjustments to apply").

Test Plan:

• Ran bin/storage upgrade --namesapce kappa123, got an adjustment using neutral language without prompting.
• Dropped a key, ran bin/storage upgrade, got normal workflow (but with more neutral language).

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11583

Differential Revision: https://secure.phabricator.com/D16509