[AIRFLOW-6239] Filter dags return by last_dagruns

[robinedwards]

Add dag_ids get parameter to last_dagruns endpoint so can filter by the
set of dag_ids present on the dags view. This is intended to speed up
the response time on systems running a large number of dags.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title.
  • https://issues.apache.org/jira/browse/AIRFLOW-6239

Description

• Here are some details about my PR, including screenshots of any UI changes:

The last_dagruns endpoint returns all dags by default. This can result in an extremely slow response time when you have a lot of dags (In our case 1500+ takes 8 seconds).

The accompanying pull request adds a dag_ids get parameter to the last_dagruns end point which is populated by the dags present on the page.

Please see related and merged issue for task_stats: https://issues.apache.org/jira/browse/AIRFLOW-6095

Tests

• My PR adds the following unit tests

(see test_views)

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

NA

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@0f9983f). Click here to learn what that means.
The diff coverage is 88.88%.

@@            Coverage Diff            @@
##             master    #6804   +/-   ##
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  Coverage          ?   84.59%           
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  Files             ?      672           
  Lines             ?    38225           
  Branches          ?        0           
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  Hits              ?    32338           
  Misses            ?     5887           
  Partials          ?        0

Impacted Files	Coverage Δ
airflow/www/views.py	76.08% <88.88%> (ø)

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