ci: clean workspace more thoroughly

This change adds execution of the `git clean -xffd` command to the
.github/actions/environment action to clean workspace more thoroughly.

NO_DOC=ci
NO_CHANGELOG=ci
NO_TEST=ci

.github/actions/environment/action.yml

@@ -82,5 +82,6 @@ runs:
         fi
         # Found that actions/checkout does not remove all temporary
         # files from previous runs, to avoid of it need to run:
+        git clean -xffd
         git submodule foreach --recursive 'git clean -xffd'
       shell: bash