timestamp: Observe user's 24-hour clock setting.
timestamp: Observe user's 24-hour clock setting.

Fixes #15791.

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