Relocate environment variable injection to before the interpreter is run #2288

Job	Run time
Check GitHub Organization	1s
tox -e py312-pip23_3_1	23m 45s
tox -e format-check,typecheck,vendor-check,package	5m 22s
tox -e py312-pip23_3_1-integration	46m 5s
./dtox.sh -e py27-pip20	11m 49s
./dtox.sh -e py35-pip20	13m 45s
./dtox.sh -e py311-pip20	14m 50s
./dtox.sh -e py311-pip22_3_1	15m 34s
./dtox.sh -e py311-pip23_1_2	20m 17s
./dtox.sh -e py312-pip23_3_1	19m 28s
./dtox.sh -e pypy310-pip20	27m 48s
./dtox.sh -e pypy310-pip22_3_1	35m 14s
./dtox.sh -e pypy310-pip23_1_2	32m 58s
./dtox.sh -e py27-pip20-integration	18m 41s
./dtox.sh -e py37-pip22_3_1-integration	39m 52s
./dtox.sh -e py37-pip23_1_2-integration	39m 34s
./dtox.sh -e py311-pip20-integration	30m 28s
./dtox.sh -e py311-pip22_3_1-integration	27m 2s
./dtox.sh -e py311-pip23_1_2-integration	37m 32s
./dtox.sh -e py312-pip23_3_1-integration	34m 33s
./dtox.sh -e pypy310-pip20-integration	38m 50s
./dtox.sh -e pypy310-pip22_3_1-integration	50m 42s
./dtox.sh -e pypy310-pip23_1_2-integration	1h 9m 4s
Gather Final Status	0s
	10h 53m 14s

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