fix(opentelemetry): adjust default value for store_spans_in_file causing traces to be produced to a file named None (#8741)

* fix(opentelemetry): adjust default value for `store_spans_in_file` causing traces to be produced to a file named `None`

The commit 5f481939d introduced `store_spans_in_file` with the default
value `None` as a string. This causes the value of `store_spans_in_file`
to be a not empty string, value=None as a string and not a null value.
The rest of the code check if the store_spans_in_file is not null which
squeezes the rest of the code. The following commit set the default
value as an empty string.

Signed-off-by: Wilfried Roset <wilfriedroset@users.noreply.github.com>

* fix(opentelemetry): No default value is better, reword changelog

Signed-off-by: Wilfried Roset <wilfriedroset@users.noreply.github.com>

---------

Signed-off-by: Wilfried Roset <wilfriedroset@users.noreply.github.com>

changelogs/fragments/8741-fix-opentelemetry-callback.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - opentelemetry callback plugin - fix default value for ``store_spans_in_file`` causing traces to be produced to a file named ``None`` (https://github.com/ansible-collections/community.general/issues/8566, https://github.com/ansible-collections/community.general/pull/8741).

plugins/callback/opentelemetry.py

@@ -85,7 +85,6 @@ DOCUMENTATION = '''
             key: disable_attributes_in_logs
         version_added: 7.1.0
       store_spans_in_file:
-        default: None
         type: str
         description:
           -  It stores the exported spans in the given file