remove unused signoff report

The signoff report command was removed in 32e3c6f9 but
the template file was kept while it should have been removed.

templates/packages/signoff_report.txt

-=== {% autoescape off %}Signoff report for [{{ repo|lower }}] ===
-{{ signoffs_url }}
-
-There are currently:
-* {{ new|length }} new package{{ new|length|pluralize }} in last {{ new_hours }} hours
-* {{ bad|length }} known bad package{{ bad|length|pluralize }}
-* {{ disabled|length }} package{{ disabled|length|pluralize }} not accepting signoffs
-* {{ complete|length }} fully signed off package{{ complete|length|pluralize }}
-* {{ incomplete|length }} package{{ incomplete|length|pluralize }} missing signoffs
-* {{ old|length }} package{{ old|length|pluralize }} older than {{ old_days }} days
-
-(Note: the word 'package' as used here refers to packages as grouped by
-pkgbase, architecture, and repository; e.g., one PKGBUILD produces one
-package per architecture, even if it is a split package.)
-
-
-{% if new %}== New packages in [{{ repo|lower}}] in last {{ new_hours }} hours ({{ new|length }} total) ==
-{% for group in new %}
-* {{ group.pkgbase }}-{{ group.version }} ({{ group.arch }}){% endfor %}
-
-{% endif %}{% regroup incomplete by target_repo as by_repo %}{% for target_repo in by_repo %}
-== Incomplete signoffs for [{{ target_repo.grouper|lower }}] ({{ target_repo.list|length }} total) ==
-{% for group in target_repo.list %}
-* {{ group.pkgbase }}-{{ group.version }} ({{ group.arch }})
-    {{ group.completed }}/{{ group.required }} signoffs{% endfor %}
-{% endfor %}
-
-{% if complete %}== Completed signoffs ({{ complete|length }} total) ==
-{% for group in complete %}
-* {{ group.pkgbase }}-{{ group.version }} ({{ group.arch }}){% endfor %}
-
-
-{% endif %}{% if old %}== All packages in [{{ repo|lower }}] for more than {{ old_days }} days ({{ old|length }} total) ==
-{% for group in old %}
-* {{ group.pkgbase }}-{{ group.version }} ({{ group.arch }}), since {{ group.last_update|date }}{% endfor %}
-
-
-{% endif %}== Top five in signoffs in last {{ new_hours }} hours ==
-{% for leader in leaders %}
-{{ forloop.counter }}. {{ leader.user }} - {{ leader.count }} signoffs{% endfor %}
-{% endautoescape %}