[Tests] `nvm_detect_profile`: refactor #1461

Job	Run time
shellcheck_matrix (bash, nvm.sh)	42s
shellcheck_matrix (sh, nvm.sh)	33s
shellcheck_matrix (dash, nvm.sh)	47s
shellcheck_matrix (ksh, nvm.sh)	39s
shellcheck_matrix (bash, install.sh)	25s
shellcheck_matrix (bash, bash_completion)	30s
shellcheck_matrix (bash, nvm-exec)	26s
shellcheck	1s
	4m 3s

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