remove old backstage injection and remove all legacy code

Overlord-Client/cmd/agent/capture/backstage_inject_windows.go

@@ -1750,12 +1750,8 @@ func findReflectiveLoaderOffset(pe []byte) (uint32, error) {
 // BackstageInjection reflective loader entry. The loader entry is exported
 // under a per-build random name of the form "x" + six lowercase hex digits
 // (generated by the DLL's build.rs), so a fixed string cannot be used to
-// find it. The legacy fixed name is still accepted so DLL artifacts produced
-// by older builds keep working.
+// find it.
 func isBackstageLoaderExport(name string) bool {
-	if name == "ReflectiveLoader" {
-		return true
-	}
 	if len(name) != 7 || name[0] != 'x' {
 		return false
 	}

Overlord-Client/cmd/agent/capture/backstage_inject_windows_test.go

@@ -115,13 +115,13 @@ func TestGetProcessesLockingFileShortPathDoesNotPanic(t *testing.T) {
 	_ = getProcessesLockingFile("a")
 }
 
-func TestIsBackstageLoaderExportSupportsBothCommandVersions(t *testing.T) {
-	for _, name := range []string{"ReflectiveLoader", "x012abc", "xffffff"} {
+func TestIsBackstageLoaderExportAcceptsRandomizedExport(t *testing.T) {
+	for _, name := range []string{"x012abc", "xffffff"} {
 		if !isBackstageLoaderExport(name) {
 			t.Fatalf("expected loader export %q to be accepted", name)
 		}
 	}
-	for _, name := range []string{"reflectiveloader", "x012ABc", "x12345", "x1234567", "other"} {
+	for _, name := range []string{"ReflectiveLoader", "reflectiveloader", "x012ABc", "x12345", "x1234567", "other"} {
 		if isBackstageLoaderExport(name) {
 			t.Fatalf("expected loader export %q to be rejected", name)
 		}