settings: Remove broken default streams error handler.
settings: Remove broken default streams error handler.

For unknown reasons, 6f7b973d3b30d96d350971c0f99390ee99c31742
introduced an invalid semi-duplicate call to ui_report.error that
passed the wrong number of parameters.

We should just call `ui_report.error`, which already had logic to
handle the distinction between 40x and 50x errors.

Fixes an issue reported in #18273.

kou/zulip,kou/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,kou/zulip,rht/zulip,andersk/zulip,punchagan/zulip,kou/zulip,rht/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,hackerkid/zulip,eeshangarg/zulip,zulip/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,hackerkid/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip,andersk/zulip,punchagan/zulip,andersk/zulip,rht/zulip,zulip/zulip,andersk/zulip,zulip/zulip,andersk/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,zulip/zulip,punchagan/zulip,zulip/zulip,rht/zulip