Remove comments about preventing sql injection with empty comment

Author: XSAM

docs/database/database-spans.md

@@ -492,8 +492,6 @@ The instrumentation implementation SHOULD **append** the comment to the end of t
 
 The instrumentation SHOULD allow users to pass a propagator to overwrite the global propagator. If no propagator is provided by the user, instrumentation SHOULD use the global propagator.
 
-If the propagator produces no output (empty context), the instrumentation SHOULD NOT inject an empty comment into the query.
-
 **Examples:**
 
 - For a query `SELECT * FROM songs` with W3C TraceContext propagator: