test: use `t.TempDir` to create temporary test directory

[Juneezee]

This pull request replaces os.MkdirTemp with t.TempDir. We can use the t.TempDir function from the testing package to create temporary directory. The directory created by t.TempDir is automatically removed when the test and all its subtests complete.

Reference: https://pkg.go.dev/testing#T.TempDir

func TestFoo(t *testing.T) {
    // before
    tmpDir, err := os.MkdirTemp("", "")
    if err != nil {
        t.Fatalf("failed to create tmp directory: %v", err)
    }
    defer func() {
        if err := os.RemoveAll(dir); err != nil {
            t.Fatal(err)
        }
    }

    // now
    tmpDir := t.TempDir()
}

[CLAassistant]

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