Unused CTSM variable

### Brief summary of bug

```
$ grep -R -n qflx_evap_can_col ./*
./biogeophys/WaterFluxType.F90:48: real(r8), pointer :: qflx_evap_can_col (:) ! col evaporation from leaves and stems (mm H2O/s) (+ = to atm)
./biogeophys/WaterFluxType.F90:239: call AllocateVar1d(var = this%qflx_evap_can_col, name = 'qflx_evap_can_col', &
```
### General bug information

**CTSM version you are using:** master/latest

**Does this bug cause significantly incorrect results in the model's science?** No

**Configurations affected:** All

### Details of bug

This should not even be allocated ever. There is qflx_evap_veg_col

### Important details of your setup / configuration so we can reproduce the bug

### Important output or errors that show the problem