wrong estimaton when there're optimizable predicates and prepared plan cache is enabled.

Bug Report

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1. Minimal reproduce step (Required)

The desensitized example is not ready yet.

We perform a prepared statement. Then we will see the row count estimation is different for col_a in (..) and col_a = .. and col_a = ...

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

master