[BUG] Output folder created before running benchmarks

[sfmig]

Describe the bug
It seems as if the teardown function is not run for the warmup of the benchmarks? I can see an output directory is created before running the benchmarks and not deleted. The output directories created during the benchmarks are correctly deleted with the teardown function.

To Reproduce
In an environment with asv run asv run -q. Once the benchmarks are done, check ~/.brainglobe/workflows/cellfinder. There shouldn't be any output directories in there (with name in the format cellfinder_output_yyyymmdd_hhmmss) after running the benchmarks, but there seems to be one whose timestamp indicates it was created before the benchmarks are run.

Expected behaviour
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Log file
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Screenshots
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Computer used (please complete the following information):

• OS: [e.g. Linux, Windows, macOS] For macOS, please specify if you have an Intel or M1 CPU (M1 is likely if your mac is new).
• Version [e.g. 18.04]
• Hardware specs [e.g. 128 GB RAM, Xeon 4114 CPU].

Additional context
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