test: Downgrade info message on removing empty directories

[hlinnaka]

It was pretty noisy. It changed from debug to info level in commit 78938d1, but I believe that was not purpose.

[github-actions]

4977 tests run: 4813 passed, 0 failed, 164 skipped (full report)

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Flaky tests (7)

Postgres 17

• test_pageserver_compaction_smoke: release-arm64
• test_ondemand_wal_download_in_replication_slot_funcs: debug-x86-64
• test_scrubber_physical_gc[4]: release-arm64

Postgres 16

• test_scrubber_physical_gc[4]: release-arm64
• test_subscriber_restart: release-x86-64

Postgres 15

• test_ondemand_wal_download_in_replication_slot_funcs: release-arm64
• test_scrubber_physical_gc[4]: release-arm64

Code coverage* (full report)

• functions: 32.1% (7436 of 23199 functions)
• lines: 49.9% (59931 of 120123 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
cc106b1 at 2024-09-22T23:34:07.396Z :recycle:}