Remove "t--lead" class from latest update article page templates

[jenniferthibault]

This styling works well on some articles that have many sections, but doesn't work well on short articles or press releases, where the entire text may be the first paragraph.

Example: https://beta.fec.gov/updates/district-court-issues-opinion-republican-party-louisiana-et-al-v-fec/

Addresses feedback from 18F/fec-style#614

Completion criteria

• Remove from press release template
• Remove from meeting agenda template (if present)
• Remove from tips for treasurers template (if present)

[noahmanger]

This change is included here https://github.com/18F/fec-cms/pull/752

[jenniferthibault]

Even better! 🎉