[AIRFLOW-5503] Fix tree view layout on HDPI screen

[robinedwards]

• Use window.devicePixelRatio to apply a multiplier to the existing dimensions falling back to 1 if its not available

Make sure you have checked all steps below.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-XXX
  • In case you are fixing a typo in the documentation you can prepend your commit with [AIRFLOW-XXX], code changes always need a Jira issue.
  • In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal (AIP).
  • In case you are adding a dependency, check if the license complies with the ASF 3rd Party License Policy.

Description

• Fix the tree view display on HDPI screens.
• See Jira issue for screenshot https://issues.apache.org/jira/browse/AIRFLOW-5503

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:
  Manually tested, very difficult to unit test screen layout.

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does
  • If you implement backwards incompatible changes, please leave a note in the Updating.md so we can assign it to a appropriate release

[feluelle]

Nice! Love it! 👍

[codecov-io]

Codecov Report

Merging #6125 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6125      +/-   ##
==========================================
- Coverage   80.12%   80.12%   -0.01%     
==========================================
  Files         607      607              
  Lines       34905    34905              
==========================================
- Hits        27967    27966       -1     
- Misses       6938     6939       +1

Impacted Files	Coverage Δ
airflow/jobs/scheduler_job.py	74.28% <0%> (-0.31%)	⬇️
airflow/utils/dag_processing.py	58.98% <0%> (+0.18%)	⬆️

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