fix: fix regression in definition resolution (#9658)

Refs https://github.com/swagger-api/swagger-js/issues/3385
Refs #9645

test/e2e-cypress/e2e/features/plugins/oas3/complex-spec.cy.js

@@ -18,19 +18,15 @@ describe("OpenAPI 3.0 complex spec with allOf and nested references", () => {
       cy.get("@scenarioSiblings")
         .find("span")
         .contains("scenarioID")
-        .should("not.exist")
+        .should("exist")
       cy.get("@scenarioSiblings")
         .find("span")
-        .contains("Scenarios (for create)")
+        .contains("Studies (for create)")
         .should("exist")
         .click()
       cy.get("@scenarioSiblings")
         .find("span")
-        .contains("scenarioID")
-        .should("exist")
-      cy.get("@scenarioSiblings")
-        .find("span")
-        .contains("#/components/schemas/unresolvedRef")
+        .contains("studyPhase")
         .should("exist")
     })
   })

test/e2e-cypress/static/documents/features/oas3-complex-spec.json

@@ -62193,9 +62193,6 @@
               "allOf": [
                 {
                   "$ref": "#/components/schemas/com.sap.ctsm.backend.core.api.study.v1.StudyAPIv1.Scenarios-create"
-                },
-                {
-                  "$ref": "#/components/schemas/unresolvedRef"
                 }
               ],
               "nullable": true