emulators/flexemu: Fix pkg-plist, rm test target

• Add two missing entries in pkg-plist, thanks to diizzy@.
• Remove test target from Makefile for now. This is solved upstream for the next upcoming release.

PR: 289725
MFH: 2025Q4
(cherry picked from commit c4a663e15a9ac4bf78332c3b4ade3b7b1c5be2cd)