Improve execution of pip during container building

- Make pip less verbose as this makes harder to investigate container
  building due to being too verbose.
- Use a bind mount to prevent pip cache from being written inside the
  container but still make use of it. This will speed-up the build
  process considerably.

src/ansible_builder/containerfile.py

@@ -94,7 +94,7 @@ def prepare(self) -> None:
                 self.steps.append('RUN /output/scripts/pip_install $PYCMD')
 
             if self.definition.ansible_ref_install_list:
-                self.steps.append('RUN $PYCMD -m pip install --no-cache-dir $ANSIBLE_INSTALL_REFS')
+                self.steps.append('RUN --mount=type=cache,dst=/root/.cache/pip $PYCMD -m pip install -q $ANSIBLE_INSTALL_REFS')
 
         self._insert_custom_steps('append_base')