ci: do not cache modified "node_modules" in "material-unit-tests" job (#29416)

Currently we cache the Material `node_modules` after
the `run_angular_material_unit_tests.sh` completed. This
means that the cache will incorrectly contain the Ivy NPM
package output which might be incompatible with the
other Material dependencies. e.g. the Material postinstall
command now uses a different NGC version that does not
work with the `typescript` version that has been specified in
the Material project.

PR Close #29416

scripts/ci/run_angular_material_unit_tests.sh

@@ -9,9 +9,6 @@ angular_dir=$(pwd)
 # Switch into Material directory.
 cd ${MATERIAL_REPO_TMP_DIR}
 
-# Install dependencies for the freshly cloned repo.
-yarn install --frozen-lockfile --non-interactive
-
 # Install this version of Angular into the freshly cloned repo.
 rm -rf ./node_modules/@angular/*
 cp -r ${angular_dir}/dist/packages-dist-ivy-aot/* ./node_modules/@angular/