Update current timestamp and logs datetime format

[edwardwang888]

I made two changes to the UI datetime format:

1. Display the date in the current timestamp. It was removed during the Airflow 2.0 UI overhaul, but I think it is still useful to have it displayed, because:
   • we now display Next Run with the date
   • it is helpful when viewing timestamps in the logs and trying to figure out how long ago something executed
2. Make sure the timezone is still displayed in the logs after changing the default timezone

---

1. Refresh the page to get initial behavior. The default timezone is UTC.

• Before:
  • Timezone is displayed in the logs before changing default timezone.
    
    
• After:
  • Current timestamp format is updated.
    
    

2. Change default timezone to PDT.

• Before:
  • Timezone disappears from logs.
    
    
• After:
  • Timezone is still displayed in logs.
    
    

3. Change default timezone back to UTC.

• Before:
  • Timezone missing from logs.
    
    
• After:
  • Timezone is still displayed in logs.
    
    

---

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