mel: empty ADE_SECTIONS

Due to how things are structured at the moment, sections which are not listed
here are not installed when the user selects the ADE for installation. We
don't want to risk missing anything at this time, so empty the variable, which
results in all package sections being installed with the ADE.

JIRA: SB-3070

Signed-off-by: Christopher Larson <kergoth@gmail.com>