puppeteer_test/16: Fix "not secure" warning hiding the button.
puppeteer_test/16: Fix "not secure" warning hiding the button.

When typing the password in Firefox,
it shows a "Not Secure" warning which was
hiding the "#get_api_key_button". You can see
the screenshot of it in #17136.

This commit fixes that issue by focusing on the button.

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