acc: Propagate user's UV_CACHE_DIR to tests (#2239)

There is a speed up in 0.5s but it is still 4.4s, so something else is
slow there.

Benchmarking bundle/templates/experimental-jobs-as-code:

```
# Without UV_CACHE_DIR
~/work/cli/acceptance/bundle/templates/experimental-jobs-as-code % hyperfine --warmup 2 'testme -count=1'
Benchmark 1: testme -count=1
  Time (mean ± σ):      4.950 s ±  0.079 s    [User: 2.730 s, System: 8.524 s]
  Range (min … max):    4.838 s …  5.076 s    10 runs

# With UV_CACHE_DIR
~/work/cli/acceptance/bundle/templates/experimental-jobs-as-code % hyperfine --warmup 2 'testme -count=1'
Benchmark 1: testme -count=1
  Time (mean ± σ):      4.410 s ±  0.049 s    [User: 2.669 s, System: 8.710 s]
  Range (min … max):    4.324 s …  4.467 s    10 runs
```

acceptance/acceptance_test.go

@@ -100,6 +100,10 @@ func testAccept(t *testing.T, InprocessMode bool, singleTest string) int {
 	// Prevent CLI from downloading terraform in each test:
 	t.Setenv("DATABRICKS_TF_EXEC_PATH", tempHomeDir)
 
+	// Make use of uv cache; since we set HomeEnvVar to temporary directory, it is not picked up automatically
+	uvCache := getUVDefaultCacheDir(t)
+	t.Setenv("UV_CACHE_DIR", uvCache)
+
 	ctx := context.Background()
 	cloudEnv := os.Getenv("CLOUD_ENV")
 
@@ -486,3 +490,16 @@ func ListDir(t *testing.T, src string) []string {
 	}
 	return files
 }
+
+func getUVDefaultCacheDir(t *testing.T) string {
+	// According to uv docs https://docs.astral.sh/uv/concepts/cache/#caching-in-continuous-integration
+	// the default cache directory is
+	// "A system-appropriate cache directory, e.g., $XDG_CACHE_HOME/uv or $HOME/.cache/uv on Unix and %LOCALAPPDATA%\uv\cache on Windows"
+	cacheDir, err := os.UserCacheDir()
+	require.NoError(t, err)
+	if runtime.GOOS == "windows" {
+		return cacheDir + "\\uv\\cache"
+	} else {
+		return cacheDir + "/uv"
+	}
+}

acceptance/bundle/templates/experimental-jobs-as-code/script

@@ -3,7 +3,7 @@ trace $CLI bundle init experimental-jobs-as-code --config-file ./input.json --ou
 cd output/my_jobs_as_code
 
 # silence uv output because it's non-deterministic
-uv sync 2> /dev/null
+uv sync -q
 
 # remove version constraint because it always creates a warning on dev builds
 cat databricks.yml | grep -v databricks_cli_version > databricks.yml.new