chore: extend length of integration test's logUnexpectedResponse (#12348)

I've observed intermittent failures in [`TestAPIAuthWithAuthorizedIntegration`](https://codeberg.org/forgejo/forgejo/actions/runs/156485/jobs/8/attempt/1#jobstep-5-1950):
```
    auth_authorized_integration_test.go:70:
        	Error Trace:	/workspace/forgejo/forgejo/tests/integration/integration_test.go:657
        	            				/workspace/forgejo/forgejo/tests/integration/auth_authorized_integration_test.go:70
        	            				/workspace/forgejo/forgejo/tests/integration/auth_authorized_integration_test.go:117
        	Error:      	Not equal:
        	            	expected: 200
        	            	actual  : 401
        	Test:       	TestAPIAuthWithAuthorizedIntegration/authorization_reducer/specific_repo_access_token
        	Messages:   	Request: GET /api/v1/repos/user2/repo1/compare/master...master
    auth_authorized_integration_test.go:70: Response length:  1801
```

I *suspect* that the cause is time-related errors in the Authorized Integration JWT, but I can't validate this because I can't reproduce the issue in local testing, and the response isn't displayed, and is just "Response length:  1801".  This PR increases the size of responses that the integration tests' `logUnexpectedResponse` will output.

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### Tests for Go changes

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I ran...
  - [x] `make pr-go` before pushing

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] This change will be noticed by a Forgejo user or admin (feature, bug fix, performance, etc.). I suggest to include a release note for this change.
- [x] This change is not visible to a Forgejo user or admin (refactor, dependency upgrade, etc.). I think there is no need to add a release note for this change.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12348
Reviewed-by: Andreas Ahlenstorf <aahlenst@noreply.codeberg.org>

tests/integration/integration_test.go

@@ -713,7 +713,7 @@ func logUnexpectedResponse(t testing.TB, recorder *httptest.ResponseRecorder) {
 		}
 
 		return
-	} else if len(respBytes) < 500 {
+	} else if len(respBytes) < 2048 {
 		// if body is short, just log the whole thing
 		t.Log("Response: ", string(respBytes))
 		return