Set autoload to 'no' for previously activated themes

[mukesh27]

By default, WordPress sets the theme_mods_* options to autoload when a theme is activated. A previous ticket, #39537, successfully addressed this by ensuring that when a different theme is activated, the previous theme's autoload settings are removed.

However, we've identified an additional issue. When users activate multiple themes over time, all corresponding options remain set to autoload. Although #39537 updated autoload settings for old and new themes, there are still lingering autoload settings for other previously activated themes.

As per the discussion in ​https://github.com/WordPress/wordpress-develop/pull/5706#issuecomment-1827606503, it's proposed that an upgrade routine should be implemented to remove autoload for these themes' options.

Trac ticket: https://core.trac.wordpress.org/ticket/59975

This PR add upgrade routine for 6.5 that set autoload to 'no' for previously activated themes.

@swissspidy i get Error: The theme "twentytwentyone" is not installed in Performance tests. Not sure if the PR changes affect their 🤔

No idea why this happens just for this PR 🤷

Seems confirmed that the Performance Test is failing due to this change for some reason as other, more recent runs, are not effected. See: ​https://github.com/WordPress/wordpress-develop/actions/workflows/performance.yml?query=

We need to debug this before committing in order to not introduce failures into trunk.

The Performance tests going fails if we update DB version. Check PR: #5716 not sure but seems there is bug Performance tests setup.

cc. @felixarntz @joemcgill @swissspidy

Oooh I know what's up!

Because of the version bump and the following checkout of the previous commit, WordPress is showing the "Database upgrade required" screen, so you first have to run the db upgrade. I tested this hypothesis in ​https://github.com/WordPress/wordpress-develop/pull/5717, where you can see that tests now pass :)

Great @swissspidy, it's fascinating how we can encounter unforeseen issues while focusing on different tasks. I suggest we commit that PR initially without altering the DB version. Afterward, we can rebase this PR, making it ready for the final commit.

Performance tests ✅

[flixos90]

In 57153:

Themes: Avoid autoloading the previous theme's theme mods when switching to another theme.

This reduces unnecessarily autoloaded data from inactive themes, which can contribute to slow database performance as part of excessive autoloading.

Props mukesh27, rajinsharwar, igmoweb, joemcgill, swissspidy, westonruter, flixos90.
Fixes #59537.
See #59975.

[flixos90]

In 57155:

Themes: Clean up inactive themes' theme mods from being autoloaded as part of upcoming 6.5 upgrade routine.

Alongside [57153], this reduces unnecessarily autoloaded data from inactive themes, which can contribute to slow database performance as part of excessive autoloading. This changeset specifically resolves the issue for existing sites.

Props mukesh27, joemcgill, swissspidy, westonruter, flixos90.
Fixes #59975.
See #39537.

Committed in https://core.trac.wordpress.org/changeset/57155