Update the schedule for MGI Dag

[amishas157]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with the jira ticket associated with the PR.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated the README with the added features, breaking changes, new instructions on how to use the repository.

What

This PR reverts the schedule for MGI Dag back to 4 pm utc

Why

MGI dag looks for success of dagrun of partner pipeline dag and the cadence should match for both. So our options are:

• Run partner pipeline dag at 5 PM UTC
• Run MGI Dag at 4 PM UTC / which this PR does
• Update MGI dag to look for different run time of partner pipeline

Known limitations

[TODO or N/A]