feat: set default value of `ssl_trusted_certificate` to `system` #17401

Job	Run time
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/plugin/[a-k]*)	33m 58s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/plugin/[l-z]*)	34m 11s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/admin t/cli t/config-center-yam...	21m 4s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/node t/pubsub t/router t/script...	24m 50s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/plugin/[a-k]*)	34m 45s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/plugin/[l-z]*)	36m 42s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/admin t/cli t/config-center-yaml t/con...	21m 10s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/node t/pubsub t/router t/script t/secr...	25m 12s
	3h 51m 52s

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