docs: remove beta references from dynamic parameters (coder#19714)

Dynamic parameters are now GA as of v2.25.0, so this PR updates the
troubleshooting section to remove outdated beta references and clarify
current support.

**Changes:**
- Updated "Template variables not showing up" section to remove beta
references
- Clarified that template variables are fully supported in GA version
- Simplified troubleshooting guidance

Fixes the outdated documentation mentioned in the Slack thread.

---------

Co-authored-by: blink-so[bot] <211532188+blink-so[bot]@users.noreply.github.com>
Co-authored-by: bpmct <22407953+bpmct@users.noreply.github.com>
Co-authored-by: david-fraley <67079030+david-fraley@users.noreply.github.com>

Author: 3 people

docs/admin/templates/extending-templates/dynamic-parameters.md

@@ -38,7 +38,7 @@ They allow you to set resource guardrails by referencing Coder identity in the `
 
 ## How to enable Dynamic Parameters
 
-In Coder v2.25.0, Dynamic Parameters are automatically enabled for new templates. You can opt-in to Dynamic Parameters for individual existing templates via template settings.
+In Coder v2.25.0 and later, Dynamic Parameters are automatically enabled for new templates. For Coder v2.24 and below, you can opt-in to Dynamic Parameters for individual existing templates via template settings.
 
 1. Go to your template's settings and enable the **Enable dynamic parameters for workspace creation** option.
 
@@ -818,9 +818,9 @@ To revert Dynamic Parameters on a template:
 
 ### Template variables not showing up
 
-Dynamic Parameters is GA as of [v2.25.0](https://github.com/coder/coder/releases/tag/v2.25.0), and this issue has been resolved. In beta ([v2.24.0](https://github.com/coder/coder/releases/tag/v2.24.0)), template variables were not supported in Dynamic Parameters.
+Dynamic Parameters are GA as of [v2.25.0](https://github.com/coder/coder/releases/tag/v2.25.0). Template variables are fully supported in Dynamic Parameters.
 
-If you are experiencing issues with template variables, try upgrading to the latest version with dynamic parameters in GA. Otherwise, please file an issue in our Github.
+If you are experiencing issues with template variables, try upgrading to the latest version. Otherwise, please file an issue in our Github.
 
 ### Can I use registry modules with Dynamic Parameters?