acc: testserver: add support for executing wheel and notebook tasks (#4507)

## Changes

Update testserver to actually execute job tasks by creating a temp venv
with uv.

**Job Execution:**
- Implement notebook task execution with magic command preprocessing
(`%python`, `%pip`)
- Add job run output retrieval for both run IDs and task run IDs
- Support `python_params` override in RunNow API
- Cache cluster virtual environments for Python wheel tasks
- Add serverless compute support

**Notebook Execution:**
- Extract wheel paths from `%pip install` commands and install them
- Mock `dbutils` module (Widgets, Library, Notebook) for compatibility
- Normalize output to match cloud behavior

**Resources:**
- Add missing instance pool "some-test-instance-pool" for variable
lookups
- Match cloud behavior for SINGLE_USER cluster drift detection. This
enables reproducing #4418 on
testserver precisely like on cloud.

**Test Outputs:**
- Update to reflect realistic Databricks behavior:
  - Modern run URLs: `/?o=[NUMID]#job/[NUMID]/run/[NUMID]`
  - Actual job names instead of generic placeholders
  - State transitions: `RUNNING` → `TERMINATED SUCCESS`
  - Multi-task job output display

## Why
Converting cloud-only tests in cloud+local speeds up
- updating test results (we only update once in local mode for
cloud+local tests, since output must match);
 - debugging test failures.

It also enables people who do not have access to integration test env to
author PRs.

The have been a couple cases where I had to debug failures in
integration_whl tests and since test takes 5-10mins, it takes a lot of
time.

## Tests
Previously cloud-only tests now work on testserver.

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: denik

acceptance/acceptance_test.go

@@ -241,6 +241,9 @@ func testAccept(t *testing.T, inprocessMode bool, singleTest string) int {
 		if os.Getenv("TEST_DEFAULT_CLUSTER_ID") == "" {
 			t.Setenv("TEST_DEFAULT_CLUSTER_ID", testserver.TestDefaultClusterId)
 		}
+		if os.Getenv("TEST_INSTANCE_POOL_ID") == "" {
+			t.Setenv("TEST_INSTANCE_POOL_ID", testserver.TestDefaultInstancePoolId)
+		}
 	}
 
 	setReplsForTestEnvVars(t, &repls)

acceptance/bundle/integration_whl/base/out.test.toml

@@ -0,0 +1 @@
+Local = true

acceptance/bundle/integration_whl/custom_params/out.test.toml

@@ -1,3 +1,9 @@
 uv venv -q .venv
 venv_activate
 uv pip install -q setuptools
+
+# On Windows, create python3 alias since some build commands use python3
+if [[ "$OSTYPE" == "msys" || "$OSTYPE" == "cygwin" || "$OSTYPE" == "win32" ]]; then
+    python3() { python "$@"; }
+    export -f python3
+fi

acceptance/bundle/integration_whl/interactive_cluster/out.test.toml

@@ -1,5 +1,5 @@
 CloudSlow = true
-Local = false
+Local = true
 
 # serverless is only enabled if UC is enabled
 RequiresUnityCatalog = true