clean `${tmpdir}` after iterations in `install_cuda_and_libraries.sh` #2459

Job	Run time
eessi_container_script (help)	1m 4s
eessi_container_script (listrepos_default)	1m 14s
eessi_container_script (listrepos_custom)	1m 39s
eessi_container_script (run)	2m 1s
eessi_container_script (shell)	1m 52s
eessi_container_script (container)	2m 0s
eessi_container_script (resume)	1m 54s
	11m 44s

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