Fix date expectation to be zero-padded

What does this MR do and why?

The date we display on the admin users page is zero-padded (e.g. Jan 02, 2023) but the expectation we have in the feature spec is blank-padded (e.g. Jan 2, 2023) so it fails when the date is from 1 - 9.

This fixes the spec to expect zero-padded date.

Related to gitlab-org/quality/engineering-productivity/master-broken-incidents#515 (closed). Example of failure: https://gitlab.com/gitlab-org/gitlab/-/jobs/3541112624.

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