[heap] Add slow test with --stress-concurrent-allocation

Test doesn't finish in 60s with --stress-concurrent-allocation, similar
to --stress-gc.

Bug: v8:10315
Change-Id: Id46231616387605ee49bfb54512828c0c8e84745
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2422000
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70035}

test/mjsunit/mjsunit.status

@@ -1452,4 +1452,9 @@
   'regress/wasm/regress-10831': [SKIP],
 }],  # ((arch == mipsel or arch == mips64el or arch == mips or arch == mips64) and not simd_mips) or (arch in [ppc64, s390x])
 
+##############################################################################
+['variant == stress_concurrent_allocation', {
+  'harmony/sharedarraybuffer-worker-gc-stress': [PASS, SLOW],
+}],  # variant == stress_concurrent_allocation
+
 ]