refactor(dns): remove unnecessary DNS client initialization #35801

Job	Run time
build / Build dependencies	17s
Schedule busted tests to run	4s
Lint and Doc tests	21s
PDK tests	3m 50s
Busted test runner 1	5m 23s
Busted test runner 2	4m 5s
Busted test runner 3	4m 45s
Busted test runner 4	4m 48s
Busted test runner 5	3m 46s
Busted test runner 6	11m 0s
Busted test runner 7	4m 58s
Cleanup and Luacov stats aggregator	1s
	43m 18s

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