Removes database migrations up to 15-3-stable-ee

What does this MR do and why?

Remove database migrations up to 20220811092253 – until 15-3-stable-ee.

Changes in this MR:

• Delete db/migrate up to 20220811092253
• Delete db/post_migrate up to 20220810093742
• Delete related specs
• Move 15-3-stable-ee db/structure.sql changes to init_structure.sql

We decided not to rename the 20211202041233_init_schema.rb file, to avoid problems with migrations

How did I perform the squash:

I used the squash script: bundle exec rake gitlab:db:squash[15-3-stable-ee]:

• Compared the diff between master and 15-3-stable-ee
• Deleted all migrations up to 15-3-stable-ee version
• Copied the structure.sql file to init_structure.sql (from 15-3-stable-ee version)

How to set up and validate locally

Generate a diff file from master branch

1. Checkout master branch

git checkout master

2. Re-create the database

gdk stop && gdk start db && bin/rails db:drop db:create

3. Migration to version 20220811092253

bin/rails db:migrate:main VERSION=20220811092253

4. Store structure.sql the diff in a temp file

cat db/structure.sql > tmp/master.diff

5. Reset the changes

git reset --hard origin

Generate a diff file from 409574-remove-old-migrations-before-20220811092253-2 branch

1. Checkout master branch

git checkout 409574-remove-old-migrations-before-20220811092253-2

2. Re-create the database

gdk stop && gdk start db && bin/rails db:drop db:create

3. Migration to version 20211202041233 (only the init_schema migration)

bin/rails db:migrate:main VERSION=20211202041233

4. Store structure.sql the diff in a temp file

cat db/structure.sql > tmp/squash.diff

5. Reset the changes

git reset --hard origin/409574-remove-old-migrations-before-20220811092253-2

Check the changes between files

git diff tmp/master.diff tmp/squash.diff

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #409574 (closed)