EXPECTED FAILURE: ERP_P256x2_Ld30.f45_f45_mg37.I2000Clm60FatesRs.derecho_intel.clm-mimicsFatesCold

### Brief summary of bug

`ERP_P72x2_Ld30.f45_f45_mg37.I2000Clm51FatesRs.cheyenne_intel.clm-mimicsFatesCold`
has been failing at SETUP (previously as a clm50 test and as a clm51 test as of today)
with `Fire emission can NOT be on when FATES is also on.`
This is an EXPECTED FAILURE. I looked into it a bit and wanted to post thoughts on fixing it.

### General bug information

**CTSM version you are using:** [output of `git describe`]
ctsm5.1.dev153

**Does this bug cause significantly incorrect results in the model's science?**
No, but it prevents testing of mimics/fates.

**Configurations affected:**
mimics and fates on at the same time.

### Details of bug

Fixing this may require pointing the mimics testmod to /basic instead of /default to avoid setting -fire_emis; however, the fix would affect all mimics tests, so I wanted to look more carefully whether this is ok to do.