fix!: update eval-tasks -> benchmarks (#1032)

# What does this PR do?

- Update `/eval-tasks` to `/benchmarks`
- ⚠️ Remove differentiation between `app` v.s. `benchmark` eval task
config. Now we only have `BenchmarkConfig`. The overloaded `benchmark`
is confusing and do not add any value. Backward compatibility is being
kept as the "type" is not being used anywhere.

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
- This change is backward compatible 
- Run notebook test with

```
pytest -v -s --nbval-lax ./docs/getting_started.ipynb
pytest -v -s --nbval-lax ./docs/notebooks/Llama_Stack_Benchmark_Evals.ipynb
```

<img width="846" alt="image"
src="https://github.com/user-attachments/assets/d2fc06a7-593a-444f-bc1f-10ab9b0c843d"
/>



[//]: # (## Documentation)
[//]: # (- [ ] Added a Changelog entry if the change is significant)

---------

Signed-off-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>
Signed-off-by: Ben Browning <bbrownin@redhat.com>
Signed-off-by: Sébastien Han <seb@redhat.com>
Signed-off-by: reidliu <reid201711@gmail.com>
Co-authored-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>
Co-authored-by: Ben Browning <ben324@gmail.com>
Co-authored-by: Sébastien Han <seb@redhat.com>
Co-authored-by: Reid <61492567+reidliu41@users.noreply.github.com>
Co-authored-by: reidliu <reid201711@gmail.com>
Co-authored-by: Yuan Tang <terrytangyuan@gmail.com>

llama_stack/distribution/ui/page/distribution/resources.py

@@ -4,8 +4,8 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+from page.distribution.benchmarks import benchmarks
 from page.distribution.datasets import datasets
-from page.distribution.eval_tasks import eval_tasks
 from page.distribution.models import models
 from page.distribution.scoring_functions import scoring_functions
 from page.distribution.shields import shields
@@ -20,7 +20,7 @@ def resources_page():
         "Shields",
         "Scoring Functions",
         "Datasets",
-        "Eval Tasks",
+        "Benchmarks",
     ]
     icons = ["magic", "memory", "shield", "file-bar-graph", "database", "list-task"]
     selected_resource = option_menu(
@@ -34,8 +34,8 @@ def resources_page():
             },
         },
     )
-    if selected_resource == "Eval Tasks":
-        eval_tasks()
+    if selected_resource == "Benchmarks":
+        benchmarks()
     elif selected_resource == "Vector Databases":
         vector_dbs()
     elif selected_resource == "Datasets":