Deprecation: remove code for config file v1 and default config file

[humitos]

This is a continuation of the work done for

• Deprecation: set dates for requiring configuration file and notify users #10351
• Deprecation: require projects define a configuration file #10342
• Deprecation: add warning for required configuration #10348
• Build: fail builds without configuration file or using v1 #10355

In that work we added notifications, warning messages and finally a feature flag to start failing the builds without a configuration file or using v1.

This commit removes all the code for config file v1 and building without a configuration file. Due to that, it also removes the code that allows users to use the older Docker images (testing, latest, stable)

This work can be merged once we enable the feature flag to fail the builds for all the projects and we are happy with the results.

Related:

• Deprecation: notification and feature flag for build.image config #10589

[humitos]

This commit removes all the code for config file v1 and building without a configuration file. Due to that, it also removes the code that allows users to use the older Docker images (testing, latest, stable)

I created a Metabase question to know how many projects are still manually specifying build.image on their config file: https://ethicalads.metabaseapp.com/question/405-projects-specifying-build-image-config-file?days=90. In the last 90 days, we currently have ~1.1k projects using build.image on their config file

[humitos]

Update this PR to disable the "Advanced settings" from Admin page: readthedocs/ext-theme#159 (comment)

[humitos]

I updated this PR with the latest changes from origin/main

This commit removes all the code for config file v1 and building without a configuration file. Due to that, it also removes the code that allows users to use the older Docker images (testing, latest, stable)

We are deprecating this on October 16th (see #10587), so we may want to merge this after that day or adapt this PR to keep build.image for now.

[ericholscher]

@humitos I saw merging this in the release tasks, but seems it's not ready?

[humitos]

He, yeah. I added this PR into this release a long time ago expecting to be ready by this time 😅

I'll update it in the next few days and ask for a review.

[humitos]

Due to #10367 (comment), I think we can merge this PR after October 16th and reduce the workload in our side.

[humitos]

This PR is ready to review and merge. After that, we can also merge https://github.com/readthedocs/readthedocs-ops/pull/1383 to remove old Docker images from AMI and builders.

[humitos]

@stsewd @ericholscher this PR removes everything related to config file v1 and default config file. I'd appreciate a review on it so we can move forward with this deprecation and finally remove this code from our repository.

Note that there is no need to do an extensive review on it since it's pretty big and, in theory, there is no changes in logic or similar. All the code removed from this PR should not be used by anybody at this point since we already passed the final removal date.

Also, since it changes 5k lines, I'd appreciate if we can merge it sooner and make the needed/small changes in another PR if required to avoid having to deal with merge conflicts again.