Couple of updates / fixes for the Image Carousel

[kgeller]

When I was going through and adding the carousel to the integration-docs, I noticed a couple of things that I thought could be better, so this PR contains those updates

1. Switches from fixed-height to max-height. Due to some images being smaller then the fixed height, we had too much whitespace, so I took a more adaptive approach and switched to the max-height.
2. Due to the switch from fixed to max height, I renamed the default and auto setting to be instead called none to better fit the updated setting name.
3. Switches when you click on the image from opening a new tab to opening a modal with the image expanded to be consistent with the regular Image directive.
4. Now that the image height isn't fixed, I instead fix the controls at 40% from the top of the smallest image (there can be quite a range in sizing).
5. Fixed indicators location to be below the images.

Note: this is technically a breaking change with the settings name update, but with it being so new I feel like it's fine.

Test directives

::::{carousel}
:max-height: medium
:::{image} https://epr.elastic.co/package/1password/1.32.0/img/1password-signinattempts-screenshot.png
:alt: Sign-in attempts
:title: Sign-in attempts
:::
:::{image} https://epr.elastic.co/package/1password/1.32.0/img/1password-itemusages-screenshot.png
:alt: Item usages
:title: Item usages
:::
::::


::::{carousel}
:max-height: medium
:::{image} https://epr.elastic.co/package/bitwarden/1.17.0/img/bitwarden-event-dashboard.png
:alt: Event dashboard
:title: Event dashboard
:::
:::{image} https://epr.elastic.co/package/bitwarden/1.17.0/img/bitwarden-group-and-collection-dashboard.png
:alt: Group and Collection dashboard
:title: Group and Collection dashboard
:::
:::{image} https://epr.elastic.co/package/bitwarden/1.17.0/img/bitwarden-member-dashboard.png
:alt: Member dashboard
:title: Member dashboard
:::
:::{image} https://epr.elastic.co/package/bitwarden/1.17.0/img/bitwarden-policy-dashboard.png
:alt: Policy dashboard
:title: Policy dashboard
:::
::::


::::{carousel}
:max-height: medium
:::{image} https://epr.elastic.co/package/armis/0.3.0/img/armis-alerts.png
:alt: Alerts Dashboard
:title: Alerts Dashboard
:::
:::{image} https://epr.elastic.co/package/armis/0.3.0/img/armis-devices.png
:alt: Devices Dashboard
:title: Devices Dashboard
:::
:::{image} https://epr.elastic.co/package/armis/0.3.0/img/armis-vulnerabilities.png
:alt: Vulnerabilities Dashboard
:title: Vulnerabilities Dashboard
:::
::::

[After] Screen recording with a couple examples from the integration docs dashboards

Screen.Recording.2025-07-31.at.10.14.01.AM.mov

[Before] Screen recording with existing carousel functionality from generated output from integration-docs PR

Screen.Recording.2025-07-31.at.10.31.10.AM.mov

Relates https://github.com/elastic/integration-experience/issues/83

[kgeller]

@reakaleek @Mpdreamz Thank you for approving and adding the label!

Would one of you mind merging as well 🙏 ? I don't have permissions (especially with the failing CI build check)