fix(gallery): render single-brace JSON in Llama 3.1 function examples

The function templates stored the few-shot JSON sample inside a Go raw
string that still had an extra pair of braces. text/template printed
that literal, so the prompt showed {{"example_name": "example_value"}}
and models copied invalid JSON.

Fixes #12890

Signed-off-by: leilei3167 <imleilei123@gmail.com>

gallery/llama3.1-instruct-grammar.yaml

@@ -40,7 +40,7 @@ config_file: |
       Think very carefully before calling functions.
       If a you choose to call a function ONLY reply in the following format with no prefix or suffix:
 
-      <function=example_function_name>{{`{{"example_name": "example_value"}}`}}</function>
+      <function=example_function_name>{{`{"example_name": "example_value"}`}}</function>
 
       Reminder:
       - If looking for real time information use relevant functions before falling back to searching on internet

gallery/llama3.1-instruct.yaml

@@ -38,7 +38,7 @@ config_file: |
       Think very carefully before calling functions.
       If a you choose to call a function ONLY reply in the following format with no prefix or suffix:
 
-      <function=example_function_name>{{`{{"example_name": "example_value"}}`}}</function>
+      <function=example_function_name>{{`{"example_name": "example_value"}`}}</function>
 
       Reminder:
       - If looking for real time information use relevant functions before falling back to searching on internet

gallery/llama3.1-reflective.yaml

@@ -40,7 +40,7 @@ config_file: |
       Think very carefully before calling functions.
       If a you choose to call a function ONLY reply in the following format with no prefix or suffix:
 
-      <function=example_function_name>{{`{{"example_name": "example_value"}}`}}</function>
+      <function=example_function_name>{{`{"example_name": "example_value"}`}}</function>
 
       Reminder:
       - If looking for real time information use relevant functions before falling back to searching on internet