Modernize temp file creation and deletion in DeferredFileOutputStreamTest

[elharo]

While experimenting I broke some things, and consequently failing tests left some untracked temporary files scattered around my git repo. This PR uses try-with-resources, JUnit 5's @tempdir, and Java 7 Files.createTempFile to more reliably cleanup after test failures.

@garydgregory

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (72da9c2) 85.97% compared to head (f41e43a) 85.97%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #535   +/-   ##
=========================================
  Coverage     85.97%   85.97%           
  Complexity     3461     3461           
=========================================
  Files           229      229           
  Lines          8191     8191           
  Branches        959      959           
=========================================
  Hits           7042     7042           
  Misses          861      861           
  Partials        288      288           

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[garydgregory]

@elharo

Toward this type of effort, I refactored some tests a while back to extend AbstractTempDirTest. Perhaps this class should do the same.

[elharo]

Thanks. I'll look at that. The one test failure on CI looks unrelated:

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Error: Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:3.1.1:deploy (default-deploy) on project commons-io: Failed to deploy artifacts: Could not transfer artifact commons-io:commons-io:pom:2.16.0-20231224.153125-11 from/to apache.snapshots.https (https://repository.apache.org/content/repositories/snapshots): authentication failed for https://repository.apache.org/content/repositories/snapshots/commons-io/commons-io/2.16.0-SNAPSHOT/commons-io-2.16.0-20231224.153125-11.pom, status: 401 Unauthorized -> [Help 1]