Don't include enqueuing info when job wasn't enqueued

[dustinbrownman]

Motivation / Background

This Pull Request was created to fix a small bug introduced in rails#48066.

Detail

This changes the logged message when a job is started. Before, the logged message always attempted to include the enqueued_at info. Unfortunately, for jobs that are run with perform_now, they are not enqueued and instead executed immediately. This left enqueued_at as nil which in turn caused a NoMethodError to be raised when attempting to call utc on the nil value.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.