test: set test-fs-cp as flaky

PR-URL: #56799
Refs: #56794
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Juan José Arboleda <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: StefanStojanovic

test/parallel/parallel.status

@@ -29,6 +29,8 @@ test-runner-watch-mode-complex: PASS, FLAKY
 test-async-context-frame: PASS, FLAKY
 # https://github.com/nodejs/node/issues/54534
 test-runner-run-watch: PASS, FLAKY
+# https://github.com/nodejs/node/issues/56794
+test-fs-cp: PASS, FLAKY
 
 # https://github.com/nodejs/node/issues/56751
 test-without-async-context-frame: PASS, FLAKY