[DEFECT] mamba might not be available in new conda environment

Thank you for the defect report

[X] I am using the latest version of RAVEN.
[X] I have read the Wiki.
[ ] I have created a minimum, reproducible example that demonstrates the defect.

Defect Description

If mamba is in the outer environment, establish_conda will not install it in the newly created environment. This can be a problem because then mamba may not be found when trying to use mamba to install.

This can result in the following error message:

... conda-forge pre-command: conda create --name raven_libraries -y -c conda-forge
Collecting package metadata (current_repodata.json): ...working... done
Solving environment: ...working... done

...

... Activating environment ...
... conda-forge command: mamba install -y -c conda-forge h5py numpy=1.22 scipy=1.9 scikit-learn=1.0 pandas xarray=2023 matplotlib=3.5 statsmodels=0.13 cloudpickle=2.2 python=3 hdf5 swig pylint coverage lxml psutil pip importlib_metadata nomkl numexpr smt setuptools liblapack=3.9.0=20_linux64_openblas numpy-financial networkx pytest dill=0.3.5 pyomo=6.4 pyutilib glpk ipopt coincbc=2.10.5 cvxpy cvxopt quadprog qpsolvers
scripts/establish_conda_env.sh: line 196: mamba: command not found

Steps to Reproduce

Install with mamba in the base library, but not on the system.

Expected Behavior

This to work.

Screenshots and Input Files

No response

OS

Linux

OS Version

No response

Dependency Manager

CONDA

For Change Control Board: Issue Review

[x] Is it tagged with a type: defect or task?
[x] Is it tagged with a priority: critical, normal or minor?
[x] If it will impact requirements or requirements tests, is it tagged with requirements?
[x] If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
[x] Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

For Change Control Board: Issue Closure

[x] If the issue is a defect, is the defect fixed?
[x] If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
[x] If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
[x] If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
[x] If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?

idaholab / raven

[DEFECT] mamba might not be available in new conda environment #2269