Quadlet - make sure the order of the UnitsDir is deterministic

Change getUnitDirs to maintain a slice in addition to the map and return the slice
Add helper functions to make the code more readable
Adjust unit tests
Restore system test

Signed-off-by: Ygal Blum <ygal.blum@gmail.com>

test/e2e/quadlet_test.go

@@ -713,7 +713,7 @@ var _ = Describe("quadlet system generator", func() {
 			Expect(session).Should(Exit(0))
 
 			current := session.ErrorToStringArray()
-			expected := "No files parsed from map[/something:{}]"
+			expected := "No files parsed from [/something]"
 
 			found := false
 			for _, line := range current {

test/system/252-quadlet.bats

@@ -221,8 +221,6 @@ EOF
 }
 
 @test "quadlet conflict names" {
-    skip "FIXME: #24047, temporary skip because this is an intense flake"
-
     # If two directories in the search have files with the same name, quadlet should
     # only process the first name
     dir1=$PODMAN_TMPDIR/$(random_string)
@@ -232,13 +230,13 @@ EOF
 
     cat > $dir1/$quadlet_file <<EOF
 [Container]
-Image=$IMAGE
+Image=quay.io/libpod/this-is-the-one:wewant
 Notify=yes
 EOF
 
     cat > $dir2/$quadlet_file <<EOF
 [Container]
-Image=$IMAGE
+Image=quay.io/libpod/bad-bad-bad:nonono
 Notify=no
 EOF
     QUADLET_UNIT_DIRS="$dir1:$dir2" run \