Fix deprecated ccache module in default generated workspace

The old module apt/ccache does not exist anymore, but the default workspace is still generated with this (commented out) module. A workspace with the apt/ccache module added builds correctly and does not complain that the package does not exist. axii workspace verify also does not complain. @kartmann @dreher is this wanted behavior?

However, if this package is added, the environment variable CCACHE defined in tools/ccache/default are not generated.

# This environment file was automatically generated by Axii on 2022-12-30 10:41:47.


_axii_env_reset


# Generated by 'workspace'
_axii_env_set ARMARX_WORKSPACE "/tmp/ccache"
_axii_env_set ARMARX_WORKSPACE_NAME "ccache"
_axii_env_set ARMARX_USER_CONFIG_DIR "/tmp/ccache/armarx_config"

# Generated by 'workspace executables'
_axii_env_prepend_to PATH "$ARMARX_WORKSPACE/.axii/bin"