Reduce quickPluginTest and quickVariantPluginTest snapshot size (#…

…12170)

* sync package-lock.json

* reduce generated examples

By default we use the default config when creating the quick tests for a
given plugin. However, this can result in _a lot_ of changes. For
example, when you update the opacity values, then these values will be
generated for each color, and for each plugin that uses that color.

You can see that behaviour in Adam's PR (#11832).
He added 6 values to the opacity configuration. This resulted in a diff
that looked like this:
```
+219,436 −9
```

This reduces the amount of examples for plugins that generate _a lot_ of
output otherwise.

* use `toMatchSnapshot`

This way all the `quickPluginTest` and `quickVariantPluginTest`
implementations are the same. This also allows us to update tests after
config changes in an easier way because they use snapshot tests right
now.

* use real colors for reduced red

This will make it a tiny bit easier to debug what's going on if we need
it in the future since it's using the same values as the real colors.