Changing ijwb plugin name to mark it as legacy (#7889)

Author: sellophane

ijwb/BUILD

@@ -51,7 +51,7 @@ stamped_plugin_xml(
     changelog_file = "//:changelog",
     description_file = "src/META-INF/description.html",
     plugin_id = "com.google.idea.bazel.ijwb",
-    plugin_name = "Bazel for IntelliJ",
+    plugin_name = "Bazel for IntelliJ (legacy)",
     # #api212: We depend on an API which is only contained in 2021.2.1+.
     since_build_numbers = {"212": "212.5080.55"},
     stamp_since_build = True,