chore: remove the shell script and docs for installing APISIX on MacO… #15939

Job	Run time
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[a-k]*)	29m 54s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[l-z]*)	28m 2s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/admin t/cli t/config-center-yaml...	23m 12s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/node t/pubsub t/router t/script ...	23m 37s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[a-k]*)	30m 56s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[l-z]*)	30m 24s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/admin t/cli t/config-center-yaml t/cont...	21m 53s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/node t/pubsub t/router t/script t/secre...	22m 22s
	3h 30m 20s

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