Move conda build tools to base environment (#39177)

* Move build tools to conda base environment in package-conda

At least one of these dependencies causes conda to be installed,
which should only be done inside the base environment.

* Move conda build tool to base env in package-standalone

conda build tools bring in conda as a dependency, so should
only be installed inside the base environment. Also, I think
conda-index is the correct dependency here.

Author: thomashampson

buildconfig/Jenkins/Conda/package-conda

@@ -82,9 +82,9 @@ done
 
 
 # Mamba
-setup_mamba $WORKSPACE/mambaforge "package-conda" true
-# CMake FindPython doesn't work correctly with conda 25.3.0
-mamba install --yes boa conda-verify versioningit conda=25.1.1
+setup_mamba $WORKSPACE/mambaforge "" true
+mamba activate base
+mamba install --yes boa conda-verify versioningit
 
 # Clean up any legacy conda-recipes git clones
 cd $WORKSPACE

buildconfig/Jenkins/Conda/package-standalone

@@ -59,9 +59,9 @@ do
 done
 
 # Mamba
-setup_mamba $WORKSPACE/mambaforge "package-standalone"
-# Pin conda to known working version. In 24.9 the post-link.bat script doesn't work.
-mamba install --yes mamba=1.5 conda-build conda=24.7
+setup_mamba $WORKSPACE/mambaforge "" true
+mamba activate base
+mamba install --yes conda-index
 
 # Build packages
 # Setup a local conda channel to find our locally built packages package. It is