clustDEgene.png is not produced by `deAnalysis.R` if there is only 2 conditions for the project

The commit https://gitlab.univ-nantes.fr/bird_pipeline_registry/DGE-pipeline/commit/f96c10642b8be52cb8da576bb3362d96dbaddef9 change the way the file clustDEgene.png is produced.

Instead of using the first page of clustDEgene.pdf, now it uses the second. If there is only 2 conditions for the project, the pdf only contains 1 page instead 2 (as the whole heatmap is the same than the heatmap limited to 2 conditions) and the file clustDEgene.png is not produced.

This leads to the following error:

Waiting at most 100 seconds for missing files.
MissingOutputException in line 175 of /some/path/DGE-pipeline/Snakefile:
Missing files after 100 seconds:
/some/path/analysePrimaire/NTS-155_ID-3_run5/NTS-155_ID-3_vsx/DE/vsx_ST__vs__vsx_CT/clustDEgene.png
This might be due to filesystem latency. If that is the case, consider to increase the wait time with --latency-wait