Disable 'Lin.Internal CList int test with Thread' under bytecode

[jmid]

OCaml's systhread context switching varies between the native and bytecode modes.
This is challenging to the experimental Thread modes and the package tests of it.
As a result

• both Lin.Internal ref int/int64 test with Thread have been disabled in bytecode mode
• the Lin.Internal CList int64 test with Thread has also been disabled in bytecode mode

This left Lin.Internal CList int test with Thread - which is marked as a positive test, but would occasionally find an unexpected counterexample in bytecode mode, causing a false alarm #358 - most recently in both bytecode trunk runs from #434.

This PR thus disables Lin.Internal CList int test with Thread in bytecode mode too.
It should eliminate another cause of false alarms.

Fixes #358

[jmid]

CI summary:

• macOS trunk failed to install dune [dune-issue] dune fails build under trunk/5.3 on macOS #433

Out of 44 workflows, 1 failed - with a genuine issue 🎉

[jmid]

CI summary for merge to main:

• macOS trunk failed to install dune [dune-issue] dune fails build under trunk/5.3 on macOS #433
• MinGW bytecode timed out in threadomain [ocaml5-issue] Windows failures on threadomain #203

Out of 45 workflows, 2 failed - with genuine issues 🎉