ci: remove retiring ubuntu-20.04 from testing (#1324) #2684

Job	Run time
wait	24s
wait2	59s
wait2-delay-120	2m 19s
wait2-delay-50	1m 15s
wait-server-starts-after-100-seconds	2m 28s
ping-cli	7s
wait3	1m 20s
wait3-for-200-seconds	4m 15s
wait4	30s
wait-multiple	2m 25s
wait-on-nextjs	23s
wait-on-vite	17s
wait-using-custom-command	34s
	17m 16s

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