Source editor dynamic height behavior causes issues in embedded contexts
### Problem Statement
The source editor's dynamic height feature causes usability problems when embedded in forms and other constrained contexts. While MR !214728 provides a workaround by opting out of this behavior for the AI Catalog Flows Form page, it doesn't address the root cause.
### Current Situation
- **Workaround implemented in !214728**: Opt-out flag for dynamic height on specific forms
- **Root cause remains**: The source editor's dynamic height behavior is not context-aware
- **Reference**: See screen recording in !214728 description and discussion in [note 2927624046](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/214728#note_2927624046)
### Expected Behavior
The source editor should intelligently handle dynamic height based on its embedding context:
- Detect when it's embedded in constrained containers (forms, modals, sidebars)
- Automatically adjust height behavior to prevent layout issues
- Provide sensible defaults that work across different use cases
### Proposed Solution
Investigate and implement one or more of the following:
1. **Context-aware height management**: Detect parent container constraints and adjust behavior automatically
2. **Improved default configuration**: Make the opt-out unnecessary by improving default behavior
3. **Container query support**: Use modern CSS container queries to adapt to available space
4. **Better API design**: Provide clearer configuration options for different embedding scenarios
### Related Issues/MRs
- !214728 - Temporary workaround for AI Catalog Flows Form
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