I wanted to search in the Maven Repositories, so I selected the Maven Repositories node in the Services, and pressed Ctrl+F. To my surprise, Find in Projects was shown instead of the Find in Repositories. It would IMHO be useful if the keyboard short cut was sensitive to the selection in this case. :)
AFAIK it's not possible to remap the Crtl-F action for a single node (or even any other non-editor context - editor is special in this area)
The component palette is sort of half way there it seems. With the GUI builder open, when a category is selected (click on category name) and you press Ctrl+F, the Find in Projects dialog appears. But a search bar is also shown at the bottom of the palette.
Whether that information is at all useful is quite debatable. :)
This old bug may not be relevant anymore. If you can still reproduce it in 8.2 development builds please reopen this issue.
Thanks for your cooperation,
NetBeans IDE 8.2 Release Boss