Consider a different tooltip for a partially ignored doctest

[ehuss]

When a doctest is partially ignored based on target, such as:

/// Example
///
/// ```ignore-wasm
/// let x = 1;
/// ```
pub fn f() {}

the documentation includes an alert that the example isn't tested (on any target):

This could be a little misleading, since the ignore statement could be for a relatively esoteric platform. But the docs seem to imply it isn't tested anywhere.

I'm not really sure what would make sense to include here. Perhaps the tooltip could be more explicit on what is being ignored?

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rustdoc 1.89.0-nightly (414482f6a 2025-05-13)
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