[v12.0/forgejo] fix: [quota.default.]TOTAL config setting supports unit suffixes (#9263)

**Backport:** https://codeberg.org/forgejo/forgejo/pulls/9252

Bring the code in line with the documentation that claims the `[quota.default].TOTAL` option supports unit suffixes.
Resolves forgejo/forgejo#8996

Co-authored-by: Brook <brook@noreply.codeberg.org>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/9263
Co-authored-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>
Co-committed-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>

modules/setting/quota_test.go

@@ -0,0 +1,63 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"fmt"
+	"testing"
+
+	"forgejo.org/modules/test"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConfigQuotaDefaultTotal(t *testing.T) {
+	iniStr := ``
+	cfg, err := NewConfigProviderFromData(iniStr)
+	require.NoError(t, err)
+	loadQuotaFrom(cfg)
+
+	assert.False(t, Quota.Enabled)
+	assert.EqualValues(t, -1, Quota.Default.Total)
+
+	testSets := []struct {
+		iniTotal    string
+		expectTotal int64
+	}{
+		{"0", 0},
+		{"5000", 5000},
+		{"12,345,678", 12_345_678},
+		{"2k", 2000},
+		{"2MiB", 2 * 1024 * 1024},
+		{"3G", 3_000_000_000},
+		{"3GiB", 3 * 1024 * 1024 * 1024},
+		{"9EB", 9_000_000_000_000_000_000},
+		{"42EB", -1},
+		{"-1", -1},
+		{"-42", -1},
+		{"-1MiB", -1},
+		{"hello", -1},
+		{"unlimited", -1},
+	}
+
+	for _, testSet := range testSets {
+		t.Run(testSet.iniTotal, func(t *testing.T) {
+			defer test.MockVariableValue(&Quota.Default.Total, -404)()
+
+			iniStr := fmt.Sprintf(`
+[quota]
+ENABLED = true
+[quota.default]
+TOTAL = %s`, testSet.iniTotal)
+
+			cfg, err := NewConfigProviderFromData(iniStr)
+			require.NoError(t, err)
+			loadQuotaFrom(cfg)
+
+			assert.True(t, Quota.Enabled)
+			assert.Equal(t, testSet.expectTotal, Quota.Default.Total)
+		})
+	}
+}