Web: Styling for DM channel header is broken

Description

Environment: Firefox/Mac on community-daily and community-release

Repro steps:
1. Go to a DM channel
2. Set a channel header if one isn't already set

Observed: The channel header text appears in a list that extends off the bottom of the header. This happens if the channel header doesn't even contain a list


Expected: The channel header is rendered as before

QA Test Steps

See description

Reporter

None

Status

Mana

None

Assignee

Unassigned

QA Assignee

None

Reporter

Harrison Healey

Epic Link

None

Fix versions

None

Mattermost Team

Unassigned

Sprint

None

Labels

None

QA Testing Areas

Channel Settings

GitHub Issue

None

Components

None
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