4 Conda Fixes to allow Conda.py to work with Micromamba

[dirkpetersen]

These 4 changes will allow EB to use Micromamba as conda / mamba replacement which is much faster

• Check for existence of micromamba first because mamba is sometimes used as alias for micromamba but typically not vice versa
• remove the --force option from command line because Micromamba does not support it. I have requested that they implement it .
• do not bootstrap config --add create_default_packages setuptools with Micromamba, there is no Python and it does not like setuptools
• delete the empty installdir os.rmdir(self.installdir) as Micromamba likes to create that itself and complains if it is already there.