Tests that pass in the DSLX interpreter, fail with deadline in the IR interpreter

**Describe the bug**

We noticed that some of the procs from the ZSTD Decoder cannot be correctly translated to the IR. In a few cases the same simulation that works with the DSLX interpreter, hangs when run with the IR interpreter.

This is a case for at least two tests:
* `RamDemux3Test` ([rule](https://github.com/antmicro/xls/blob/zstd_ir_problem/xls/modules/zstd/BUILD#L2398))
* `ZstdDecoderInternalTest` ([rule](https://github.com/antmicro/xls/blob/zstd_ir_problem/xls/modules/zstd/BUILD#L1563))

**To Reproduce**

Steps to reproduce the behavior:
1. Checkout to the [zstd_ir_problem](https://github.com/antmicro/xls/tree/zstd_ir_problem) branch
2. Run `bazel run //xls/modules/zstd:ram_demux3_dslx_test` to run the test with the IR interpreter
3. Observe the following error:
```
Executing tests from //xls/modules/zstd:ram_demux3_dslx_test
-----------------------------------------------------------------------------
[ RUN UNITTEST ] RamDemux3Test
qE0130 14:34:39.920672 1784807 run_routines.cc:110] Internal error: DEADLINE_EXCEEDED: Exceeded limit of 100000 ticks of the proc network before expected output produced
[ FAILED ] RamDemux3Test: internal error: DEADLINE_EXCEEDED: Exceeded limit of 100000 ticks of the proc network before expected output produced
```
4. Open the BUILD file and remove the `evaluator="ir-interpreter"` option from the `ram_demux3_dslx_test` rule.
5. Run the test with DSLX interpreter and see the test passing

**Expected behavior**

The test should give the same result when run with DSLX and IR interpreters.