[SYCL][Fusion][NFC] Comment fusion abortion on inter-fusion dependency (#12678)

Add comment stating event dependencies on any commands part of a
different active fusion leads to the abortion of that fusion.

---------

Signed-off-by: Victor Perez <[email protected]>

Author: victor-eds

sycl/source/detail/scheduler/graph_builder.cpp

@@ -966,8 +966,8 @@ Scheduler::GraphBuildResult Scheduler::GraphBuilder::addCG(
           ++Ev;
           continue;
         }
-        // Handle event dependencies on any commands part of another active
-        // fusion.
+        // Event dependencies on commands part of another active fusion are
+        // handled by cancelling fusion in that other queue.
         if (EvDepCmd->getQueue() != Queue && isPartOfActiveFusion(EvDepCmd)) {
           printFusionWarning(
               "Aborting fusion because of event dependency from a "