GH-44728: [Python] Trigger manual Garbage collection before checking allocated bytes for dlpack tests

[raulcd]

Rationale for this change

test_dlpack started failing for several jobs on CI due to our tests deallocating memory:

        allocated_bytes = pa.total_allocated_bytes()
        try:
            return f(*args, **kwargs)
        finally:
>           assert pa.total_allocated_bytes() == allocated_bytes
E           assert 3728 == 7440

What changes are included in this PR?

Trigger a gc.collect before checking initial allocated bytes.

Are these changes tested?

Yes via CI

Are there any user-facing changes?

No

• GitHub Issue: #44728

[github-actions[bot]]

:warning: GitHub issue #44728 has been automatically assigned in GitHub to PR creator.

[raulcd]

@github-actions crossbow submit test-conda-python-3.11-pandas-latest-numpy-latest

[github-actions[bot]]

Revision: 345cede50be95f8ab5b71249100d30c3e454061e

Submitted crossbow builds: ursacomputing/crossbow @ actions-b5f54acb57

Task	Status
test-conda-python-3.11-pandas-latest-numpy-latest

[raulcd]

@github-actions crossbow submit test-conda-python-3.11-pandas-latest-numpy-latest

[github-actions[bot]]

Revision: 46920cd8528d3b40883045a200bf440eaa24a4f4

Submitted crossbow builds: ursacomputing/crossbow @ actions-8c113f5e44

Task	Status
test-conda-python-3.11-pandas-latest-numpy-latest

[raulcd]

@github-actions crossbow submit pandas

[raulcd]

@github actions crossbow submit test-conda-python-3.9

[github-actions[bot]]

Revision: 46920cd8528d3b40883045a200bf440eaa24a4f4

Submitted crossbow builds: ursacomputing/crossbow @ actions-2a3e520bab

Task	Status
test-conda-python-3.10-pandas-latest-numpy-latest
test-conda-python-3.11-pandas-latest-numpy-1.26
test-conda-python-3.11-pandas-latest-numpy-latest
test-conda-python-3.11-pandas-nightly-numpy-nightly
test-conda-python-3.11-pandas-upstream_devel-numpy-nightly
test-conda-python-3.9-pandas-1.1.3-numpy-1.19.5

[raulcd]

@github-actions crossbow submit test-conda-python-3.9

[raulcd]

@jorisvandenbossche I found what was going on

[github-actions[bot]]

Revision: 46920cd8528d3b40883045a200bf440eaa24a4f4

Submitted crossbow builds: ursacomputing/crossbow @ actions-5b0f156d29

Task	Status
test-conda-python-3.9

[conbench-apache-arrow[bot]]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit 54f8cf9d969b1a1f668c4102a26df57282bc977c.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 1 possible false positive for unstable benchmarks that are known to sometimes produce them.