test: use `T.TempDir` to create temporary test directory (#21043)

A testing cleanup. 

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. 

This saves us at least 2 lines (error check, and cleanup) on every instance, or in some cases adds cleanup that we forgot.

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

```go
func TestFoo(t *testing.T) {
	// before
	tmpDir, err := os.MkdirTemp("", "")
	require.NoError(t, err)
	defer os.RemoveAll(tmpDir)

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

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

1 files changed, 1 insertions, 8 deletions

diff --git a/tests/integration/create_no_session_test.go b/tests/integration/create_no_session_test.go
index c9b90974d7..c617b1828a 100644
--- a/tests/integration/create_no_session_test.go
+++ b/tests/integration/create_no_session_test.go
@@ -14,7 +14,6 @@ import (
 
 	"code.gitea.io/gitea/modules/json"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/routers"
 	"code.gitea.io/gitea/tests"
 
@@ -70,13 +69,7 @@ func TestSessionFileCreation(t *testing.T) {
 	config.Provider = "file"
 
 	// Now create a temporaryDirectory
-	tmpDir, err := os.MkdirTemp("", "sessions")
-	assert.NoError(t, err)
-	defer func() {
-		if _, err := os.Stat(tmpDir); !os.IsNotExist(err) {
-			_ = util.RemoveAll(tmpDir)
-		}
-	}()
+	tmpDir := t.TempDir()
 	config.ProviderConfig = tmpDir
 
 	newConfigBytes, err := json.Marshal(config)