Do not decorate tabs for BUILD files in non-bazel projects (#6925)

If a project isn't imported then do not try to decorate
as otherwise tab name has a full path to file.

base/src/com/google/idea/blaze/base/editor/BazelEditorTabTitleProvider.java

@@ -2,6 +2,7 @@
 
 import com.google.idea.blaze.base.lang.buildfile.psi.BuildFile;
 import com.google.idea.blaze.base.settings.Blaze;
+import com.google.idea.blaze.base.settings.BlazeImportSettings.ProjectType;
 import com.intellij.openapi.fileEditor.impl.EditorTabTitleProvider;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
@@ -15,6 +16,10 @@ private static boolean requiresDecoration(Project project, String fileName) {
   @Override
   public @Nullable String getEditorTabTitle(@NotNull Project project,
       @NotNull VirtualFile virtualFile) {
+    if (Blaze.getProjectType(project) == ProjectType.UNKNOWN) {
+      return null;
+    }
+
     var fileName = virtualFile.getName();
     if (!requiresDecoration(project, fileName)) {
       return null;