(you don't have to strictly follow this form)

**Describe the bug**
When using `ORDER BY column_name COLLATE 'en'`, `COLLATE` is ignored if `column_name` is the primary key
 
**How to reproduce**
* version 21.1.2
* `CREATE TABLE` statements for all tables involved:
```
CREATE TABLE test.test_collation
(
    `v` String,
    `v2` String
)
ENGINE = MergeTree
ORDER BY v
SETTINGS index_granularity = 8192
```
* Sample data:
```
insert into test.test_collation values ('A', 'A')
insert into test.test_collation values ('B', 'B')
insert into test.test_collation values ('C', 'C')
insert into test.test_collation values ('a', 'a')
insert into test.test_collation values ('b', 'b')
insert into test.test_collation values ('c', 'c')
```
* Queries to run that lead to unexpected result
Primary key
```
SELECT *
FROM test.test_collation
ORDER BY v ASC COLLATE 'en'

Query id: fa84ae7a-abe7-4886-99cd-eba7ad5d5fc4

┌─v─┬─v2─┐
│ A │ A  │
│ B │ B  │
│ C │ C  │
│ a │ a  │
│ b │ b  │
│ c │ c  │
└───┴────┘
```
Separate column
```
SELECT *
FROM test.test_collation
ORDER BY v2 ASC COLLATE 'en'

Query id: 04401f85-3cb2-442c-8c89-e3328d1615cd

┌─v─┬─v2─┐
│ a │ a  │
│ A │ A  │
│ b │ b  │
│ B │ B  │
│ c │ c  │
│ C │ C  │
└───┴────┘
```

**Expected behavior**
Both of these queries to return the rows in the same order

{
        chain.finalize();
        if (!finalized)
        {
            finalize(chain, where_step_num, query);
            finalized = true;
        }
        chain.clear();
    };
    if (storage)
    {
        query_analyzer.makeSetsForIndex(query.where());
        query_analyzer.makeSetsForIndex(query.prewhere());
    }
    {
        ExpressionActionsChain chain(context);
        Names additional_required_columns_after_prewhere;
        if (storage && (query.sampleSize() || settings.parallel_replicas_count > 1))
        {
            Names columns_for_sampling = metadata_snapshot->getColumnsRequiredForSampling();
            additional_required_columns_after_prewhere.insert(additional_required_columns_after_prewhere.end(),
                columns_for_sampling.begin(), columns_for_sampling.end());
        }
        if (storage && query.final())
        {
            Names columns_for_final = metadata_snapshot->getColumnsRequiredForFinal();
            additional_required_columns_after_prewhere.insert(additional_required_columns_after_prewhere.end(),
                columns_for_final.begin(), columns_for_final.end());
        }
        if (storage && filter_info_)