Mermaid diagrams are not rendered inside HTML tags
So, it seems that [our implementation](https://gitlab.com/gitlab-org/gitlab_kramdown/-/blob/5314e0bff59fd314ff8517a178147aa65a02d674/lib/gitlab_kramdown/converter/gitlab_html.rb#L27-45) in the `gitlab_kramdown` side contradicts with Kramdown's way to render markdown inside HTML tags.
# Reproduce
By trying all options listed in https://kramdown.gettalong.org/syntax.html#html-blocks, create an HTML file from the Markdown doc:
```shell
cat index.md | kramdown >! index.html
```
## `markdown="1"`
> If an HTML tag has an attribute `markdown="1"`, then the default mechanism for parsing syntax in this tag is used.
Markdown:
````md
<details markdown="1"><summary>Click to view the graph</summary>
Reference pipeline: <https://gitlab.com/gitlab-org/gitlab/pipelines/135236627>
```mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
```
</details>
````
HTML:
```html
<details>
<summary>Click to view the graph</summary>
<p>Reference pipeline: <a href="https://gitlab.com/gitlab-org/gitlab/pipelines/135236627">https://gitlab.com/gitlab-org/gitlab/pipelines/135236627</a></p>
<p><code>mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
</code></p>
</details>
```
## `markdown="block"`
> If an HTML tag has an attribute `markdown="block"`, then the content of the tag is parsed as block level elements.
Markdown:
````md
<details markdown="block"><summary>Click to view the graph</summary>
Reference pipeline: <https://gitlab.com/gitlab-org/gitlab/pipelines/135236627>
```mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
```
</details>
````
HTML:
```html
<details>
<summary>Click to view the graph</summary>
<p>Reference pipeline: <a href="https://gitlab.com/gitlab-org/gitlab/pipelines/135236627">https://gitlab.com/gitlab-org/gitlab/pipelines/135236627</a></p>
<p><code>mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
</code></p>
</details>
```
## `markdown="span"`
> If an HTML tag has an attribute `markdown="span"`, then the default mechanism for parsing syntax in this tag is used.
Markdown:
````md
<details markdown="span"><summary>Click to view the graph</summary>
Reference pipeline: <https://gitlab.com/gitlab-org/gitlab/pipelines/135236627>
```mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
```
</details>
````
HTML:
```html
<details><summary>Click to view the graph</summary>
Reference pipeline: <a href="https://gitlab.com/gitlab-org/gitlab/pipelines/135236627">https://gitlab.com/gitlab-org/gitlab/pipelines/135236627</a>
<code>mermaid
graph LR
subgraph "No needed jobs";
1-1["danger-review (3.5 minutes)"];
click 1-1 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8100542&udv=0"
1-50["docs lint (6.75 minutes)"];
click 1-50 "https://app.periscopedata.com/app/gitlab/652085/Engineering-Productivity---Pipeline-Build-Durations?widget=8356757&udv=0"
end
</code>
</details>
```
issue