System note text for relating issues is misleading

Summary

When an issue is related to another issue as "blocking" or "blocked by", a new system note service is created with text "User X marked this issue as related to Y"

This is not accurate, ideally the note should say something like "User X marked this issue as blocked by Y"

A possible solution is to override relate_issuable method in EE and update the text depending on relation type.

Steps to reproduce

1. Go to issue show page and relate the issue with another issue (and use blcoked/blocked by relation)
2. Check created system note text

Also I'm qutie sure that this note - #356684 (comment 973579148) - was added when I marked the issue as blocked by.

Example Project

What is the current bug behavior?

What is the expected correct behavior?

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes