feat(monitors): improvements to app metric equation rendering

[bcoe]

Before

• Leaks internal details about how an equation is formatted that a user never sees making the text we show confusing.
• Doesn't fit on the screen and is clipped, making things more confusing.

After

Inspired by how the AI Query Agent renders its suggested filters:

Note

There are similar improvements we can make to non-equation metrics monitors, but figured I'd start here for now since users have complained specifically about this experience.

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[github-actions]

📊 Type Coverage Diff

Metric	Before	After	Delta
Coverage	94.35%	94.35%	±0%
Typed	134,148	134,177	🟢 +29
Untyped	8,040	8,042	🔴 +2

🔍 2 new type safety issues introduced

any-typed symbols (2 new)

File	Line	Detail
static/app/components/charts/components/tooltip.tsx	246	visibleSeriesParams (var)
static/app/components/charts/components/tooltip.tsx	309	serie (param)

This is informational only and does not block the PR.