:nodoc: for abstract_mysql_adapter
Merge pull request #17411 from mcfiredrill/doc-change-column-default-abstract-mysql-adapter

document change_column and change_column_default for abstract_mysql_adapter [ci skip]
On larger screens the email preview iframe is being limited to a height of 800 pixels, and the full available screen size is not being used.
Merge pull request #17429 from edwinwills/full-height-email-preview

The email preview iframe height is fixed and does not scale to the browser size
[ci skip] Fixes typos in section 2.7 "Rails Html Sanitizer", adds content to section 2.8 "Rails DOM Testing"
Merge pull request #17431 from hbriggs/upgrade_guide_2.7_2.8

Update 2.7 & 2.8 of upgrading_ruby_on_rails.md [ci skip]
correct GlobalID mixin name in the guides
Merge pull request #17432 from cmoylan/update-active-job-guide

correct GlobalID mixin name in the guides
Fix typo at form_helper docs [ci skip]