Remove credentials from xhr request. Add techdocs-backend changeset

.changeset/clean-plums-crash.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-techdocs-backend': patch
+---
+
+Forward authorization header on backend request if present

.changeset/old-coats-suffer.md

@@ -2,4 +2,4 @@
 '@backstage/plugin-techdocs': minor
 ---
 
-Add authorization header on techdocs api requests
+Add authorization header on techdocs api requests. Breaking change as clients now needs the Identity API.

plugins/techdocs/src/api.ts

@@ -171,7 +171,6 @@ export class TechDocsStorageApi implements TechDocsStorage {
     const request = await fetch(
       `${url.endsWith('/') ? url : `${url}/`}index.html`,
       {
-        credentials: 'include',
         headers: token ? { Authorization: `Bearer ${token}` } : {},
       },
     );