stream: fix stream pruning being too aggressive

Pruning of StreamBufferBlocks could remove blocks that fell entirely
after the target offset due to a logic error. This could lead to data
being evicted that was still meant to be processed in theapp-layer
parsers.

Bug: OISF#4953.
(cherry picked from commit 78f5e08)

src/util-streaming-buffer.c

@@ -412,7 +412,7 @@ static void SBBPrune(StreamingBuffer *sb)
     StreamingBufferBlock *sbb = NULL, *safe = NULL;
     RB_FOREACH_SAFE(sbb, SBB, &sb->sbb_tree, safe) {
         /* completely beyond window, we're done */
-        if (sbb->offset > sb->stream_offset) {
+        if (sbb->offset >= sb->stream_offset) {
             sb->head = sbb;
             break;
         }