Refactor LineChartExample for simpler line series configuration

[hunterg325]

Refactor LineChartExample for simpler line series configuration

• Reduce generated line data size from 5000 to 1000 points to make the example lighter and faster to render.[page:1]
• Simplify the line series configuration by removing custom name, lineStyle, areaStyle, and explicit axis configuration so the example focuses on the core chart usage.[page:1]
• Keep two minimal line series definitions using the shared generateLineData helper for a clearer, more maintainable demo setup.[page:1]