QUnit tests: get rid of unnecessary timezone tests (#31355) #24116

Job	Run time
Build DevExtreme	11m 6s
Get changed demos	0s
Build Demos	7m 17s
Check generated demos	2m 6s
Check TS	1m 57s
Lint code base	0s
testcafe-${{ matrix.CONSTEL }}-${{ matrix.THEME }}	0s
merge-artifacts	-1s
	22m 25s

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