feat(presets)!: drop renovate.json fallback

[viceice]

Changes

Remove the fallback to renovate.json preset when default.json is not found.

NOTE: Review with ignore whitespace changes. 😉

TODO

• fix conflicts
• throw config error when fallback found

Context

• Default org config #22212
• Fallback to renovate.json file as a preset is deprecated, please use a default.json file instead #23419
• feat(presets): warn on renovate.json fallback #24263
• v38 planning #27992

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[secustor]

Outside of coverage LGTM

Also not approving as it targeted at the main branch ;)

[rarkins]

@nabeelsaabna can you find out how many Fallback to renovate.json file as a preset is deprecated, please use a default.json file instead. log messages we see daily in the hosted app?

@viceice we may want to upgrade this to a WARN for a longer period of time first

[nabeelsaabna]

@rarkins in the last 7 days we have 4234 unique repositories with this message in the github hosted app

[viceice]

ok I've created another PR to warn now, so we can drop later

• feat(presets): warn on renovate.json fallback #24263

[rarkins]

I don't think we can do this yet

[rarkins]

I think we have too many still using this in the Renovate app.

[viceice]

I think we have too many still using this in the Renovate app.

so what's the next step to get existing users to change their settings?

[rarkins]

We could improve our efficiency by remembering these fallbacks in repositoryCache: #28008

[rarkins]

I'm not sure we can merge this for a long time, certainly not in v38. So let's close this PR but keep the branch in place