Simplify Scene dock Filter Nodes placeholder

[timothyqiu]

The current placeholder is too long for regular usage.

It was introduced to enhance the discoverability of the filtering syntax.

But nowadays, the filter options are available in the related menus. It's no longer necessary to use this placeholder I think.

Context Menu	Three-dots Menu

[passivestar]

I agree because I think search needs to be improved with more filter types and complex expressions to be more useful for large projects (i.e see this and this). Teaching all of the new syntax via placeholder text won't be possible, it will need to be made discoverable by other means

[KoBeWi]

The menu options don't mention shorthands (t: g:). Maybe they could be in the tooltip?