puppeteer: Set visible: true to fix flakes.
puppeteer: Set visible: true to fix flakes.

These `waitForSelector`s appear just after page loads.
Though they worked most of the times, a few clicks weren't
getting registered because of these selectors not appearing
and thus causing flakes as the modal takes time to appear.
Adding visible: true asserts that it's visible and not just present.

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