Resolve "Issue weight empty state in sidebar doesn't match other blocks"

Closes #2010

See merge request !1512

Remove N+1 queries for Groups::AnalyticsController

Closes gitlab-ce#22940 and #1886

See merge request !1514

Closes gitlab-org/gitlab-ce#22940, #1886

Allow downgrade when no users were added in previous period

See merge request !1490

Currently a customer can't downgrade because validations will fail given
the historical max will be greater than the current active users. If
customer hasn't added more users in the previous period we should
compare against the current active users instead.

Change full colors to a more harmonious palette

See merge request !1504

Show loading icon when changing filter in add issues modal EE port

See merge request !1505

# Conflicts:
#	app/assets/stylesheets/framework/variables.scss

Closes #29615