Revert "minor #12673 [Form] [Hackday] [2.7] Add a deprecation note about the `form_enctype` helper (mrcmorales)"

This reverts commit e8d98578f4bc5037b8b36968843a7bee1d44641d, reversing
changes made to 0c7df5898f322102a82e54900519197e0e6bdb7a.
[2.7] Allow 3.0 requirements
Merge branch '2.7'

* 2.7: (26 commits)
  Updated generateSql tool
  Fix grammar
  Fix the implementation of deprecated Locale classes
  Fix phpdoc and coding standards
  Replace usages of the deprecated TypeTestCase by the new one
  Remove usages of deprecated constants
  Update functional tests to use the PSR NullLogger
  Updated the SQL data generated from the generateSql tool
  Updated generateSql tool
  fix regression in form tests after pr #13027 | Q             | A | ------------- | --- | Bug fix?      | yes | New feature?  | no | BC breaks?    | no | Deprecations? | no | Tests pass?   | yes | Fixed tickets | - | License       | MIT | Doc PR        | -
  [FrameworkBundle] added a test router for the buil-in web server
  Make fabbot happy
  Clean up testing
  No global state for isolated tests and other fixes
  No global state for isolated tests and other fixes
  fix #10054 - form data collector with dynamic fields
  [TwigBundle] Moved the setting of the default escaping strategy from the Twig engine to the Twig environment
  [Debug] fix checkip6
  [HttpFoundation] fixed error when an IP in the X-Forwarded-For HTTP header contains a port
  [2.7] Allow 3.0 requirements
  ...