i18n: Fix translation bug in stream creation page.
i18n: Fix translation bug in stream creation page.

This change fixes a translation bug that prevented a string in the
message retention dropdown options from getting translation.
Removing the space properly matched the string with the translated
strings.

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