Small improvements for Airflow UI

[mnojek]

I slightly improved some small UI elements that were a bit off.
Changes:

• Removed btn-sm class that made the buttons next to each DAG on DAGs list not centered perfectly.
• Changed everywhere the spelling of DAGs (made the last letter lowercase in 'DAGS' word)
• Changed the 'Conn Type' and 'Conn Id' to 'Connection Type' Connection Id' (not sure why this whas abbreviated everywhere, but if I am not aware of something, let me know and I can revert this change)
• Fixed strange use of punctuation marks inside a view when trying to mark DAG run as failed
• Changed font size inside DAG run circle from 8 to 9. It makes it a lot more readable and it can still fit even 4-digit numbers. I think we can even go with 10, but then 4-digit numbers slightly overlay the circle (who have 4-digit runs though?).

Here I highlighted with red color the old font size and misaligned icons inside button. The green highlights the elements after changes.

If there are any other places that I missed or there is something that shouldn't be changed or maybe the change should be reflected in some places that I missed - let me know!

[potiuk]

Reopened to rebuild

[github-actions]

The PR most likely needs to run full matrix of tests because it modifies parts of the core of Airflow. However, committers might decide to merge it quickly and take the risk. If they don't merge it quickly - please rebase it to the latest main at your convenience, or amend the last commit of the PR, and push it with --force-with-lease.

[uranusjr]

Changes in this file are too objective subjective (typo) to me. They may not be wrong (although I don't see how they improve what), but don't fit well with the rest of the PR.

[mnojek]

This dot just doesn't look nice in the UI. Short sentences or instructions don't need a dot at the end, especially if they are not included in some bigger text wall, but are just a short notification or instruction. I know it's subjective, but I think it's commonly accepted. Sentences like 'Click OK', 'Check your filters', 'Insert value' do not require a full stop at the end. Also, it is perceived as insincere or even rude nowadays. In my opinion, it looks just better in this case.