Initialize checks for unused ".cache/json" directory before deleting all HTML and CSS

[ascorbic]

Preliminary Checks

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Description

The initialize function checks for the existence of .cache/json, and if it doesn't exist then deletes all existing HTML and CSS files. This directory is unused when using lmdb-store. This means that if no pages have changed then all the pages on the site are deleted.

There are several issues that I can see here:

1. initialize is checking for a folder that isn't used anymore
2. initialize doesn't check if lmdb data store is missing
3. missing pages aren't regenerated

Reproduction Link

https://github.com/ascorbic/cache-json-bug

Steps to Reproduce

1. Clone repo (or just start with any Gatsby 4 repo)
2. Run gatsby build
3. Delete empty .cache/json directory
4. Run gatsby build again

Expected Result

public/index.html should exist

Actual Result

All HTML and CSS files are deleted and no re-created

Environment

System:
    OS: macOS 11.4
    CPU: (8) x64 Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.5.0 - ~/.nvm/versions/node/v16.5.0/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.19.1 - ~/.nvm/versions/node/v16.5.0/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 93.0.4577.82
    Safari: 14.1.1
  npmPackages:
    gatsby: ^4.0.0-zz-next.1 => 4.0.0-zz-next.1

Config Flags

No response