**Describe the bug**
Under certain conditions the equals comparison between String and Date yields the wrong result. Range Comparisons with greather-than-equals returns the correct result set.

**How to reproduce**
* Which ClickHouse server version to use: 21.2.5.5 (latest at the time of this issue)
* Which interface to use, if matters: HTTP (but should not matter)

```sql
CREATE TABLE default.myTable (
	myDay Date,
	myOrder Int32,
	someData String
) 
ENGINE = ReplacingMergeTree
PARTITION BY floor(toYYYYMMDD(myDay), -1)
ORDER BY (myOrder)
;

INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-01', 1);
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-02', 2); // This row should be returned
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-03', 3);

SELECT * FROM default.myTable mt
WHERE myDay = '2021-01-02';
```

**Expected behavior**
The last query in the example should yield the marked row. Instead it returns a empty result set.

There must be a connection to the used `PARTITION KEY`. The issue fails to reproduce as soon as I do any changes to the `PARTITION KEY` setting.

const auto & children = action.node->children;
        if (action.node->type == ActionsDAG::ActionType::FUNCTION
            && children.size() == 1
            && children[0]->result_name == expr_name)
        {
            if (!action.node->function_base->hasInformationAboutMonotonicity())
                return false;
            
            IFunction::Monotonicity monotonicity = action.node->function_base->getMonotonicityForRange(*out_type, Field(), Field());
            if (!monotonicity.is_always_monotonic)
                return false;
            
            std::tie(out_value, out_type) = applyFunctionForFieldOfUnknownType(
                action.node->function_builder,
                out_type, out_value);
            expr_name = action.node->result_name;
            
            auto it = key_columns.find(expr_name);
            if (key_columns.end() != it)
            {
                out_key_column_num = it->second;
                out_key_column_type = sample_block.getByName(it->first).type;
                found_transformation = true;
                break;
            }
        }
    }
    return found_transformation;
}
bool KeyCondition::canConstantBeWrappedByFunctions(