fix: clarify description of LoggerConfig.trace_based (#4930)

Minor clarification. The reader of the current description may think
that if `trace_based = true` then log records not associated with a
trace should not be recorded (which is not true).

The proposed change is more precise and follows other parts of the
specification that use normative language such as


https://github.com/open-telemetry/opentelemetry-specification/blob/e4ad687a9e89abf9d59ee394ee10977d041b71ba/specification/logs/sdk.md?plain=1#L213-L217


https://github.com/open-telemetry/opentelemetry-specification/blob/e4ad687a9e89abf9d59ee394ee10977d041b71ba/specification/logs/sdk.md?plain=1#L249-L252


https://github.com/open-telemetry/opentelemetry-specification/blob/e4ad687a9e89abf9d59ee394ee10977d041b71ba/specification/logs/sdk.md?plain=1#L264-L266

Moreover, define the behavior when `trace_based = false` using normative
language.

---------

Co-authored-by: Tigran Najaryan <4194920+tigrannajaryan@users.noreply.github.com>

Author: pellared

specification/logs/sdk.md

@@ -206,10 +206,13 @@ It consists of the following parameters:
   affected by this parameter and therefore bypass minimum severity filtering.
 
 * `trace_based`: A boolean indication of whether the logger should
-  only process log records associated with sampled traces.
+  drop log records associated with an unsampled trace.
 
   If not explicitly set, the `trace_based` parameter MUST default to `false`.
 
+  If `trace_based` is `false`, log records MUST NOT be affected because of this
+  parameter.
+
   If `trace_based` is `true`, log records associated with unsampled traces MUST
   be dropped by the `Logger`. A log record is considered associated with an unsampled trace
   if it has a valid `SpanId` and its `TraceFlags` indicate that the trace is unsampled.