improvement: operation path + summary overflow styling (via #5184)

* improvement: operation path + summary overflow styling

* inject zero-width spaces for better path breaking

* migrate 4867 regression test to tolerate new ZWSPs

* rm `dev-helpers/doc.yaml`

test/e2e-cypress/tests/bugs/4867.js

@@ -7,8 +7,8 @@ describe("#4867: callback parameter rendering", () => {
       .contains("Callbacks")
       .click()
 
-      .get(".callbacks-container")
-      .contains("http://$request.query.url")
+      .get(".callbacks-container .opblock-summary-path")
+      .should("have.attr", "data-path", "http://$request.query.url")
       .click()
 
       .get(".parameters-container")