resolves #32705

Update schema.rb documentation [CI SKIP]

The documentation previously claimed that `db/schema.rb` was "the
authoritative source for your database schema" while simultaneously
also acknowledging that the file is generated. These two statements are
incongruous and the guides accurately call out that many database
constructs are unsupported by `schema.rb`. This change updates the
comment at the top of `schema.rb` to remove the assertion that the file
is authoritative.

The documentation also previously referred vaguely to "issues" when
re-running old migrations. This has been updated slightly to hint at the
types of problems that one can encounter with old migrations.

In sum, this change attempts to more accurately capture the pros, cons,
and shortcomings of the two schema formats in the guides and in the
comment at the top of `schema.rb`.

[Derek Prior & Sean Griffin]
Co-authored-by: NSean Griffin <sean@seantheprogrammer.com>

https://github.com/sparklemotion/sqlite3-ruby/blob/v1.3.13/lib/sqlite3/statement.rb#L101-L104

Use strict_encode64 instead of gsub newline for ScreenshotHelper

Save a hash allocation in MySQL statement pool

Ensure that other processes like ImageMagick and FFmpeg see the complete contents of the file.

Use ImageProcessing gem for ActiveStorage variants

There's no need to wrap the statement in a hash with a single key.

Halve memory allocation in S3Service#download

Aws::S3::Object#get returns a response with object content wrapped in an
in-memory StringIO object. StringIO#read will return a copy of the
content, which is not necessary because we can return the content
directly using StringIO#string. This halves memory allocation of
S3Service#download, because we remove unnecessary content duplication.

* Remove key from session by using session.delete

You are not deleting a key from session when you assign nil to that key.

* Update guides on how to destroy a user session

In this commit, the user id is removed from session and controller's variables related to the user are nullified.

[Rafael Mendonça França + Rafael Barbolo]

Update rails-ujs readme

This is not true anymore, the image will be downloaded into a temporary
file in a streaming fashion.

Since other views use the `h2` tag, should also use `h2` on
`missing_exact_template.html.erb`.

https://github.com/rails/rails/blob/76acaf6eb9ef3635e4c6f2ca9dba34edb50f541d/actionpack/lib/action_dispatch/middleware/templates/rescues/routing_error.html.erb#L5
https://github.com/rails/rails/blob/76acaf6eb9ef3635e4c6f2ca9dba34edb50f541d/actionpack/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb#L11
https://github.com/rails/rails/blob/76acaf6eb9ef3635e4c6f2ca9dba34edb50f541d/actionpack/lib/action_dispatch/middleware/templates/rescues/unknown_action.html.erb#L5

Update results of command in Testing guides [ci skip]

Refactor guides javascripts

* Remove `$` prefix from all variables (`$` prefix means jQuery object)
* Old browsers doesn't support forEach. So use for instead of forEach.

* Results of command in testing guides are different from actual ones.
* Updated them.

✂ jQuery for Rails Guides

Fix indentation manually

Rubocop auto-correct doesn't work well, so I fixed indentation manually.

Gracefully handle extra "controller" when generating controller

In the previous code incorrectly removes intermediate words.

Rubocop 0.54

Fix duplicated suffix for JobGenerator

Add test case to ChannelGeneratorTest

* Add a test case to ensure avoid duplicated suffix in channel generator

Reset RAW_POST_DATA between test requests