ProblemList compiler/loopstripmining/BackedgeNodeWithOutOfLoopControl.java
to reduce the noise in the JDK16 CI.

So far we have 80 sightings...

Here's the proposed context diff:

$ git diff
diff --git a/test/hotspot/jtreg/ProblemList.txt b/test/hotspot/jtreg/ProblemList.txt
index a5afc8bc4e5..680184d8403 100644
--- a/test/hotspot/jtreg/ProblemList.txt
+++ b/test/hotspot/jtreg/ProblemList.txt
@@ -64,6 +64,8 @@ compiler/rtm/print/TestPrintPreciseRTMLockingStatistics.java 8183263 generic-x64
 
 compiler/c2/Test8004741.java 8235801 generic-all
 
+compiler/loopstripmining/BackedgeNodeWithOutOfLoopControl.java 8255120 generic-all
+
 #############################################################################
 
 # :hotspot_gc