tests: Simplify by always clearing IP limits in rate_limit_rule.
tests: Simplify by always clearing IP limits in rate_limit_rule.

The only use case of rate_limit_rule which does not clear the
RateLimitedIPAddr history is test_hit_ratelimits_as_remote_server,
which is not made any worse by clearing out the IP history for a
non-existent `api_by_remote_server` domain.

zulip/zulip,andersk/zulip,andersk/zulip,andersk/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,kou/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,zulip/zulip,rht/zulip,zulip/zulip,zulip/zulip,rht/zulip,eeshangarg/zulip,zulip/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,kou/zulip,kou/zulip