debugger: Fix environment variables not being substituted in debug tasks (#31198)

Release Notes:

- Debugger Beta: Fixed a bug where environment variables were not
substituted in debug tasks in some cases.

Co-authored-by: Anthony Eid <hello@anthonyeid.me>
Co-authored-by: Remco Smits <djsmits12@gmail.com>

crates/debugger_ui/src/session/running.rs

@@ -927,6 +927,7 @@ impl RunningState {
                     .ok_or_else(|| anyhow!("{}: is not a valid adapter name", &adapter))
                     .map(|adapter| adapter.config_from_zed_format(zed_config))??;
                 config = scenario.config;
+                Self::substitute_variables_in_config(&mut config, &task_context);
             } else {
                 anyhow::bail!("No request or build provided");
             };