test(sidecar): drop stub-mode placeholder tautology tests

internal/sidecar/embed_test.go

@@ -1,20 +0,0 @@
-//go:build !withsidecar
-
-package sidecar
-
-import "testing"
-
-func TestStub_IsPlaceholder(t *testing.T) {
-	if !IsPlaceholder() {
-		t.Errorf("default build should be a placeholder")
-	}
-	if EmbeddedSize() != 0 {
-		t.Errorf("stub should have empty embedded JAR, got size %d", EmbeddedSize())
-	}
-}
-
-func TestStub_ExtractFails(t *testing.T) {
-	if _, err := Extract(t.TempDir()); err == nil {
-		t.Fatal("expected Extract to fail in stub mode")
-	}
-}