Fix non-ASCII search on database (#18437)

Use `ToASCIIUpper` for SQLite database on issues search, this because `UPPER(x)` on SQLite only transforms ASCII letters. Resolves #18429

modules/util/util_test.go

@@ -186,3 +186,37 @@ func Test_OptionalBool(t *testing.T) {
 	assert.Equal(t, OptionalBoolTrue, OptionalBoolParse("t"))
 	assert.Equal(t, OptionalBoolTrue, OptionalBoolParse("True"))
 }
+
+// Test case for any function which accepts and returns a single string.
+type StringTest struct {
+	in, out string
+}
+
+var upperTests = []StringTest{
+	{"", ""},
+	{"ONLYUPPER", "ONLYUPPER"},
+	{"abc", "ABC"},
+	{"AbC123", "ABC123"},
+	{"azAZ09_", "AZAZ09_"},
+	{"longStrinGwitHmixofsmaLLandcAps", "LONGSTRINGWITHMIXOFSMALLANDCAPS"},
+	{"long\u0250string\u0250with\u0250nonascii\u2C6Fchars", "LONG\u0250STRING\u0250WITH\u0250NONASCII\u2C6FCHARS"},
+	{"\u0250\u0250\u0250\u0250\u0250", "\u0250\u0250\u0250\u0250\u0250"},
+	{"a\u0080\U0010FFFF", "A\u0080\U0010FFFF"},
+	{"lél", "LéL"},
+}
+
+func TestToUpperASCII(t *testing.T) {
+	for _, tc := range upperTests {
+		assert.Equal(t, ToUpperASCII(tc.in), tc.out)
+	}
+}
+
+func BenchmarkToUpper(b *testing.B) {
+	for _, tc := range upperTests {
+		b.Run(tc.in, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				ToUpperASCII(tc.in)
+			}
+		})
+	}
+}