test: remove useless `DotEnvTest` test #13499

Job	Run time
Setup PHP Version for Code Coverage	2s
Others (8.2) / Sanity Tests	1m 52s
Others (8.1) / Sanity Tests	2m 38s
Others (8.4) / Sanity Tests	1m 53s
Others (8.3) / Sanity Tests	1m 53s
Upload coverage results to Coveralls	0s
SeparateProcess	0s
DatabaseLive	0s
CacheLive	0s
	8m 18s

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