wrongly skip plan cache with predicate simplification

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

CREATE TABLE t1 (
pk INTEGER PRIMARY KEY,
col_time TIME DEFAULT NULL,
col_varchar VARCHAR(1) DEFAULT NULL,
KEY (col_varchar)
);
INSERT INTO t1 VALUES(5, '11:03:56', 'I');
PREPARE st FROM
"SELECT * FROM t1
WHERE pk = 5 AND (col_time, col_varchar) IN ((23, 'Y'), (92, 'W'))";
EXECUTE st;

2. What did you expect to see? (Required)

No warnings

3. What did you see instead (Required)

Level	Code	Message
Warning	1105	skip prepared plan-cache: True/False predicate simplification is triggered

4. What is your TiDB version? (Required)

ac812ca