Fix warnings from tests

[rly]

Motivation

Recent changes to HDMF remove the warning that there are no cached namespaces when loading namespaces and adds the warning that an object A with a DynamicTableRegion that points to table B is being added to another object C but table B and object C do not share an ancestor. Some tests fail or raise new warnings because of these changes. This PR addresses those.

Also updates the test_read_dandi.py test to not run when calling pytest and to not exceed the 360 minutes runtime allowed by GitHub Actions.

How to test the behavior?

Run test suite and also observe CI logs

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running flake8 from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.

[codecov]

Codecov Report

Merging #1778 (0cecd30) into dev (4656c08) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev    #1778   +/-   ##
=======================================
  Coverage   91.98%   91.98%           
=======================================
  Files          27       27           
  Lines        2608     2608           
  Branches      681      681           
=======================================
  Hits         2399     2399           
  Misses        134      134           
  Partials       75       75           

Flag	Coverage Δ
integration	71.24% <ø> (ø)
unit	83.66% <ø> (ø)

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[oruebel]

Looks good to me