Fix nil pointer access in AfterEach of failed e2e test cases #3623

Job	Run time
e2e (v1.28.13, v0.53.5)	24m 3s
e2e (v1.28.13, v0.53.5)	34m 22s
e2e (v1.28.13, v0.65.0)	20m 48s
e2e (v1.28.13, v0.65.0)	34m 27s
e2e (v1.31.0, v0.53.5)	22m 27s
e2e (v1.31.0, v0.53.5)	37m 43s
e2e (v1.31.0, v0.65.0)	23m 50s
e2e (v1.31.0, v0.65.0)	35m 2s
integration (v1.28.13, v0.53.5)	28m 57s
integration (v1.28.13, v0.53.5)	28m 57s
integration (v1.28.13, v0.65.0)	28m 38s
integration (v1.28.13, v0.65.0)	28m 38s
integration (v1.31.0, v0.53.5)	28m 42s
integration (v1.31.0, v0.53.5)	28m 42s
integration (v1.31.0, v0.65.0)	28m 55s
integration (v1.31.0, v0.65.0)	28m 55s
test-docker-build (base)	44s
test-docker-build (base)	44s
test-docker-build (git)	1m 2s
test-docker-build (git)	1m 2s
test-docker-build (image-processing)	48s
test-docker-build (image-processing)	48s
unit	3m 25s
unit	3m 25s
test-docker-build (waiter)	34s
test-docker-build (waiter)	34s
	7h 56m 12s

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