Mismatch between `max_trace_verbosity` and `vtrace_fmt!` codegen output

**Describe the bug**

Even though one can specify a high value for `"max_trace_verbosity` in the codegen options.
Only `vtrace_fmt!` that use log level `u32:0` are emited in SytemVerilog.

**To Reproduce**

I created a small example to reproduce the problem.
It is available on the following branch:
* https://github.com/antmicro/xls/tree/vtrace_fmt

Steps to reproduce the behavior:
1. Get the code of the example
2. execute `bazel build //xls/examples:vtrace_fmt_verilog`
3. obsrve that only a `$display("Verbosity level 0");` is avaliable in the generated verilog

**Expected behavior**
The verilog should also contain `$display("Verbosity level 10");` since `max_trace_verbosity` was set to `100` for the `//xls/examples:vtrace_fmt_verilog` target