quic: improve recv coalescing test sizes

Signed-off-by: James M Snell <jasnell@gmail.com>
Assisted-by: Opencode:Opus 4.6
PR-URL: #63267
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: jasnell

test/parallel/test-quic-stream-recv-coalescing.mjs

@@ -17,15 +17,17 @@ if (!hasQuic) {
 const{ listen, connect }=awaitimport('../common/quic.mjs');
 const{drainableProtocol: dp}=awaitimport('stream/iter');
 
-// Payloads of varying sizes. Exercises different coalescing paths:
-// Small (below frame size), medium (a few frames), large (many frames).
+// Payloads of varying sizes with diverse prime factors to exercise
+// different flow control boundary alignments. Avoids round multiples
+// of 1000 so that frame boundaries, accumulation buffer thresholds,
+// and flow control windows are hit at irregular offsets.
 constpayloadSizes=[
-100,// Small: fits in a single frame
-5_000,// Medium: a few frames
-64_000,// Large: triggers buffer-full flush
-1_000,// Small again after large
-200_000,// Very large: well beyond 64 KB buffer
-500,// Small tail
+97,// Small prime: fits in a single frame
+4_999,// Medium prime: a few frames
+65_521,// Largest prime below 64 KB buffer flush threshold
+1_153,// Small prime after large
+196_613,// Large prime: well beyond 64 KB buffer
+509,// Small prime tail
 ];
 consttotalBytes=payloadSizes.reduce((a,b)=>a+b,0);