From '/glade/scratch' to '/glade/derecho/scratch'

**Bug Subject:**
As NCAR supercomputer users: From '/glade/scratch' to '/glade/derecho/scratch'

**Bug Content:**

### Brief summary of bug

As shown in [NCAR HPC Docs](https://ncar-hpc-docs.readthedocs.io/en/latest/storage-systems/glade/#overview), `/glade/scratch/username` no longer exists. The new scratch path is `/glade/derecho/scratch/username`. However, there is a hard-coded `/glade/scratch/username` path in certain CTSM modules, making it difficult to run CTSM successfully.

### General bug information

**CTSM version you are using:** ctsm5.2.010

**Does this bug cause significantly incorrect results in the model's science?** Yes

**Configurations affected:** Yes

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

Run this on NCAR Derecho/Casper supercomputer.

- **Compset:** I2000Clm60FatesSpRsGs
- **Resolution:** f45_g37
- **Machine:** NCAR Derecho/Casper
- **Compiler:** Not sure
- **XML or namelist changes:** None

### Important output or errors that show the problem

wukoutian@casper20:~/clm_tutorial_cases/I2000_CTSM_FATESsp> ./case.setup
Setting resource.RLIMIT_STACK to -1 from (8388608, -1)
job is case.run USER_REQUESTED_WALLTIME None USER_REQUESTED_QUEUE None WALLTIME_FORMAT %H:%M:%S
Creating batch scripts
Writing case.run script from input template /glade/u/home/wukoutian/CTSM/ccs_config/machines/template.case.run
Creating file .case.run
Writing case.st_archive script from input template /glade/u/home/wukoutian/CTSM/ccs_config/machines/template.st_archive
Creating file case.st_archive
Creating user_nl_xxx files for components and cpl
ERROR: Could not make directory '/glade/scratch/wukoutian/I2000_CTSM_FATESsp/bld/cpl/obj', error: [Errno 13] Permission denied: '/glade/scratch'

**How to fix the bug**

For your reference, this bug might have been noticed and partially fixed, as shown in the code search for `scratch`:
https://github.com/search?q=repo%3AESCOMP%2FCTSM%20scratch&type=code

You may also want to also fix all the code related to the retired NCAR `Cheyenne` supercomputer:
https://github.com/search?q=repo%3AESCOMP%2FCTSM%20cheyenne&type=code

When writing commands or scripts, you can use the environment variable `$SCRATCH` to represent your scratch directory. Here are examples for both a command line and a Python script.

### Command Line Example
In a command line script, you can use `$SCRATCH` directly. For example, if you want to list the contents of your scratch directory, you can use:

```bash
ls $SCRATCH
```

Or, if you want to copy a file to your scratch directory:

```bash
cp myfile.txt $SCRATCH/
```

### Python Script Example
In a Python script, you can access the `$SCRATCH` environment variable using the `os` module. Here's an example of how you can do this:

```python
import os

# Get the path to the scratch directory from the environment variable
scratch_dir = os.getenv('SCRATCH')

# Use the scratch directory path in your script
if scratch_dir:
print(f"Scratch directory: {scratch_dir}")

# Example: creating a file in the scratch directory
file_path = os.path.join(scratch_dir, 'myfile.txt')
with open(file_path, 'w') as f:
f.write("This is a test file in the scratch directory.")

print(f"File created at: {file_path}")
else:
print("SCRATCH environment variable is not set.")
```

This script retrieves the path of the scratch directory from the `SCRATCH` environment variable and then uses it to create a file in that directory.

By using the `$SCRATCH` variable, you ensure that your scripts and commands are flexible and can adapt to different environments where the actual path of the scratch directory might vary.