fix(css): simplify misleading grid syntax examples

[xopsio]

Simplifies two grid syntax examples by removing repeated line names that can be misleading.

Fixes #41176

[github-actions]

Preview URLs (1 page)

• /en-US/docs/Web/CSS/Reference/Properties/grid

Flaws (8)

Found an unexpected or unresolvable flaw? Please report it here.

URL: /en-US/docs/Web/CSS/Reference/Properties/grid
Title: grid
Flaw count: 8

• broken_links:
  • Link /en-US/docs/Web/CSS/Reference/Values/flex doesn't resolve
  • Link /en-US/docs/Web/CSS/Reference/Values/number-token doesn't resolve
• macros:
  • Macro cssinfo produces link /en-US/docs/Web/CSS/grid-column-gap which is a redirect
  • Macro cssinfo produces link /en-US/docs/Web/CSS/grid-row-gap which is a redirect
  • Macro cssinfo produces link /en-US/docs/Web/CSS/grid-column-gap which is a redirect
  • Macro cssinfo produces link /en-US/docs/Web/CSS/grid-row-gap which is a redirect
  • Macro cssinfo produces link /en-US/docs/Web/CSS/grid-column-gap which is a redirect
  • and 1 more flaws omitted