feat: set default value of `ssl_trusted_certificate` to `system` #1159

Job	Run time
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/http3/admin)	10m 26s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/plugin/[a-k]*)	10m 17s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/plugin/[l-z]*)	10m 27s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/admin t/cli t/config-center-yam...	10m 26s
build (ubuntu-latest, linux_openresty, lua-resty-worker-events, t/node t/pubsub t/router t/script...	10m 25s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/http3/admin)	10m 25s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/plugin/[a-k]*)	10m 25s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/plugin/[l-z]*)	10m 27s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/admin t/cli t/config-center-yaml t/con...	10m 25s
build (ubuntu-latest, linux_openresty, lua-resty-events, t/node t/pubsub t/router t/script t/secr...	10m 26s
	1h 44m 9s

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