[improve][io] Use try-with-resources for some locations

[AROP-REPLICATION]

Fixes #24899

Motivation

use try-with stmt to close the resoure in:
1、org.apache.pulsar.io.flume.source.AbstractSource#process ObjectOutput
2、org.apache.pulsar.io.file.utils.GZipFiles#isGzip PushbackInputStream

Modifications

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:

[lhotari]

There's no actual resource leaks in these cases. The unclosed resources are memory-only and there's no actual effect in making the changes in this PR. However, it's not a harmful change either.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.30%. Comparing base (ebfff58) to head (072b85d).
⚠️ Report is 349 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24900      +/-   ##
============================================
- Coverage     74.31%   74.30%   -0.01%     
- Complexity    33843    33851       +8     
============================================
  Files          1913     1913              
  Lines        149325   149322       -3     
  Branches      17332    17332              
============================================
- Hits         110966   110952      -14     
- Misses        29503    29519      +16     
+ Partials       8856     8851       -5     

Flag	Coverage Δ
inttests	26.41% <ø> (+0.06%)	⬆️
systests	22.81% <0.00%> (-0.11%)	⬇️
unittests	73.82% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ava/org/apache/pulsar/io/file/utils/GZipFiles.java	68.18% <100.00%> (ø)
.../apache/pulsar/io/flume/source/AbstractSource.java	83.33% <100.00%> (-0.99%)	⬇️

... and 68 files with indirect coverage changes

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