Fix test_shell_command_interruption flake (#10649)

## Human summary
Sandboxing (specifically `LandlockRestrict`) is means that e.g. `sleep
10` fails immediately. Therefore it cannot be interrupted.

In suite::interrupt::test_shell_command_interruption, sleep 10 is issued
at 17:28:16.554 (ToolCall: shell_command {"command":"sleep 10"...}),
then fails at 17:28:16.589 with duration_ms=34, success=false,
exit_code=101, and
    Sandbox(LandlockRestrict).

## Codex summary
- set `sandbox_mode = "danger-full-access"` in `interrupt` and
`v2/turn_interrupt` integration tests
- set `sandbox: Some(SandboxMode::DangerFullAccess)` in
`test_codex_jsonrpc_conversation_flow`
- set `sandbox_policy: Some(SandboxPolicy::DangerFullAccess)` in
`command_execution_notifications_include_process_id`

## Why
On some Linux CI environments, command execution fails immediately with
`LandlockRestrict` when sandboxed. These tests are intended to validate
JSON-RPC/task lifecycle behavior (interrupt semantics, command
notification shape/process id, request flow), but early sandbox startup
failure changes turn flow and can trigger extra follow-up requests,
causing flakes.

This change removes environment-specific sandbox startup dependency from
these tests while preserving their primary intent.

## Testing
- not run in this environment (per request)

codex-rs/app-server/tests/suite/codex_message_processor_flow.rs

@@ -36,7 +36,7 @@ use std::path::Path;
 use tempfile::TempDir;
 use tokio::time::timeout;
 
-const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
+const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(20);
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
 async fn test_codex_jsonrpc_conversation_flow() -> Result<()> {
@@ -76,6 +76,7 @@ async fn test_codex_jsonrpc_conversation_flow() -> Result<()> {
     let new_conv_id = mcp
         .send_new_conversation_request(NewConversationParams {
             cwd: Some(working_directory.to_string_lossy().into_owned()),
+            sandbox: Some(SandboxMode::DangerFullAccess),
             ..Default::default()
         })
         .await?;

codex-rs/app-server/tests/suite/interrupt.rs

@@ -147,7 +147,7 @@ fn create_config_toml(codex_home: &Path, server_uri: String) -> std::io::Result<
             r#"
 model = "mock-model"
 approval_policy = "never"
-sandbox_mode = "read-only"
+sandbox_mode = "danger-full-access"
 
 model_provider = "mock_provider"
 

codex-rs/app-server/tests/suite/v2/turn_interrupt.rs

@@ -129,7 +129,7 @@ fn create_config_toml(codex_home: &std::path::Path, server_uri: &str) -> std::io
             r#"
 model = "mock-model"
 approval_policy = "never"
-sandbox_mode = "workspace-write"
+sandbox_mode = "danger-full-access"
 
 model_provider = "mock_provider"
 

codex-rs/app-server/tests/suite/v2/turn_start.rs

@@ -1652,6 +1652,7 @@ async fn command_execution_notifications_include_process_id() -> Result<()> {
                 text: "run a command".to_string(),
                 text_elements: Vec::new(),
             }],
+            sandbox_policy: Some(codex_app_server_protocol::SandboxPolicy::DangerFullAccess),
             ..Default::default()
         })
         .await?;