Remove shimo integration

.rubocop_todo/rspec/expect_change.yml

.rubocop_todo/rspec/factory_bot/avoid_create.yml

.rubocop_todo/rspec/feature_category.yml

app/assets/images/logos/shimo.svg

app/controllers/projects/integrations/shimos_controller.rb

app/models/integration.rb

app/models/integrations/shimo.rb

app/models/project.rb

app/views/projects/integrations/shimos/show.html.haml

...trics/counts_all/20211028210001_projects_shimo_active.yml

...metrics/counts_all/20211028210002_groups_shimo_active.yml

...rics/counts_all/20211028210003_instances_shimo_active.yml

...s_all/20211028210004_projects_inheriting_shimo_active.yml

...nts_all/20211028210005_groups_inheriting_shimo_active.yml

config/routes/project.rb

data/deprecations/15-7-deprecate-shimo-integration.yml

db/docs/integrations.yml

doc/.vale/gitlab/spelling-exceptions.txt

doc/api/graphql/reference/index.md

doc/development/integrations/index.md