Add Gitaly data to the usage ping

See merge request gitlab-org/gitlab-ce!29893

Backport changes made by EE to various YAML configuration files

See merge request gitlab-org/gitlab-ce!29606

This commits adds support for metrics dashboards
for embedding. If the flag 'embedded' is provided
to the environments/id/metrics_dashboard endpoint,
the response will be suitable for embedding in
issues or other content.

This is a precursor for support for embedding
metrics in GFM.

Gitaly data wasn't available to the team, an this change is a first
iteration towards understanding what data we need and how to interpret
it. Later more values will be added.

For now the most important thing is the filesystem String Array, as that
includes data on ext4 exposure and NFS.

Part of: https://gitlab.com/gitlab-org/gitlab-ce/issues/60602

To make this happen, we need to conditionally add the group_saml
strategy when running tests, but only on EE. This requires some changes
to Gitlab.ee? so that it can be used before/without loading the Rails
environment. We also have to change how we require a few files, so this
can run outside of Rails.

Gitlab::JsonCache#parse_value ensure string

Closes #63510

See merge request gitlab-org/gitlab-ce!29885

Remove import columns from projects table

See merge request gitlab-org/gitlab-ce!29863

This adds a `markdown_field` to our types.

Using this helper will render a model's markdown field using the
existing `MarkupHelper` with the context of the GraphQL query
available to the helper.

Having the context available to the helper is needed for redacting
links to resources that the current user is not allowed to see.

Because rendering the HTML can cause queries, the complexity of a
these fields is raised by 5 above the default.

The markdown field helper can be used as follows:

      ```
      markdown_field :note_html, null: false
      ```

This would generate a field that will render the markdown field `note`
of the model. This could be overridden by adding the `method:`
argument. Passing a symbol for the method name:

      ```
      markdown_field :body_html, null: false, method: :note
      ```

It will have this description by default:

> The GitLab Flavored Markdown rendering of `note`

This could be overridden by passing a `description:` argument.

The type of a `markdown_field` is always `GraphQL::STRING_TYPE`.

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21497, we
migrated all project import data into a separate table,
`project_import_data`.  In addition, we also added:

```
ignore_column :import_status, :import_jid, :import_error
```

In https://gitlab.com/gitlab-com/gl-infra/production/issues/908, we
observed some of these `import_error` columns consumed megabytes of
error backtraces and caused slow loading of projects whenever a `SELECT
* from projects` query loaded the row into memory.

Since we have long migrated away from these columns, we can now drop
these columns entirely.