GH-48079: [CI] Fix a typo in util_free_space.sh

[starpit]

Rationale for this change

Fixes a typo in util_free_space.sh. See #48079

What changes are included in this PR?

Simple typo fix.

Are these changes tested?

This is a CI script.

Are there any user-facing changes?

No

• GitHub Issue: [CI] Typo in util_free_space.sh? #48079

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[github-actions]

⚠️ GitHub issue #48079 has been automatically assigned in GitHub to PR creator.

[raulcd]

Thanks for your contribution @starpit !

[kou]

+1

[conbench-apache-arrow]

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