- instead of using properties
- backward compatibility has to be kept for now

We are deprecating this service in favor of instance wide clusters.
Therefore we removed some code that is not anymore needed for a
readonly cluster and also we added some flags to allow for this
deprecation. These flags are to be removed in the next release when
we finally completelly remove KubernetesService.

- create tables for storing issue trackers properties
- add model and basic logic & spec

- rewords examples starting with 'should'
- rewords examples starting with 'it'

Note: I had to manually fixup "onlies" to "only"

Adds `# frozen_string_literal: true` to spec/models ruby files

[10.6] Prevent notes on confidential issues from being sent to chat

See merge request gitlab/gitlabhq!2366
# Conflicts:
#	app/helpers/services_helper.rb

Merge branch 'security-10-3-do-not-expose-passwords-or-tokens-in-service-integrations-api' into 'security-10-3'

Filter out sensitive fields from the project services API

See merge request gitlab/gitlabhq!2281

(cherry picked from commit 476f2576444632f2a9a61b4cead9c1077f2c81d7)

2bcbbda0 Filter out sensitive fields from the project services API

Remove superfluous lib: true, type: redis, service: true, models: true, services: true, no_db: true, api: true
Signed-off-by: Rémy Coutable <remy@rymai.me>

This commit adds a number of _html columns and, with the exception of Note,
starts updating them whenever the content of their partner fields changes.

Note has a collision with the note_html attr_accessor; that will be fixed later

A background worker for clearing these cache columns is also introduced - use
`rake cache:clear` to set it off. You can clear the database or Redis caches
separately by running `rake cache:clear:db` or `rake cache:clear:redis`,
respectively.