Cleanup HOMEBREW_TEMP handling

- Ensure that `HOMEBREW_TEMP` is only displayed in `brew config` when
  it's non-default.
- Attempt to create a missing `HOMEBREW_TEMP` directory rather than
  failing to `realpath`. Note this will still fail on permissions errors
  which is to be expected.

audit: exact match throttled formula names

brew.sh: Don't allow system tmp dirs as prefixes

components_redundancy: audit `stable do` without a head or devel spec

audit: exempt versioned formulae from new formula audit

Show tapped casks.

Bump github-pages from 186 to 187 in /docs

Re-enable tests by removing a stray rspec `:focus`

Bumps [github-pages](https://github.com/github/pages-gem) from 186 to 187.
- [Release notes](https://github.com/github/pages-gem/releases)
- [Commits](https://github.com/github/pages-gem/compare/v186...v187

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

install: don't exit on Homebrew.failed?

This will be set if e.g. pinned packages aren't being upgraded.

Fixes #4388.

Bump rubocop from 0.57.1 to 0.57.2 in /Library/Homebrew/test

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 0.57.1 to 0.57.2.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop-hq/rubocop/compare/v0.57.1...v0.57.2

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Additionally, assign HOMEBREW_TEMP based on the host
system (/tmp for Linux, /private/tmp for macOS).

We provide a /private/tmp fallback in bin/brew, so
this is no longer necessary.

Upgrade to Rubocop 0.57.2

Remove unneeded RuboCop comment.