**Describe the bug**
Using `ALTER LIVE VIEW view REFRESH` results in an exception.

**How to reproduce**
* Connected to ClickHouse server version 20.8.1 revision 54438
* `CREATE TABLE` statements for all tables involved
```
clicktest :) SHOW CREATE table0

SHOW CREATE TABLE table0

┌─statement─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ CREATE TABLE default.table0
(
    `d` Date,
    `a` String,
    `b` UInt8,
    `x` String,
    `y` Int8
)
ENGINE = MergeTree()
ORDER BY d
SETTINGS index_granularity = 8192 │
└───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

1 rows in set. Elapsed: 0.006 sec.
```
* Queries to run that lead to unexpected result
```
ClickHouse client version 20.8.1.4447 (official build).
Connecting to localhost:9000 as user default.
Connected to ClickHouse server version 20.8.1 revision 54438.

clicktest :) SET allow_experimental_live_view=1

SET allow_experimental_live_view = 1

Ok.

0 rows in set. Elapsed: 0.003 sec.

clicktest :) CREATE LIVE VIEW live1 AS SELECT * FROM table0

CREATE LIVE VIEW live1 AS
SELECT *
FROM table0

Ok.

0 rows in set. Elapsed: 0.008 sec.

clicktest :) ALTER LIVE VIEW live1 REFRESH

ALTER LIVE VIEW live1
    REFRESH

Received exception from server (version 20.8.1):
Code: 49. DB::Exception: Received from localhost:9000. DB::Exception: RWLockImpl::getLock(): RWLock is already locked in exclusive mode.

0 rows in set. Elapsed: 0.005 sec.
```
**Expected behavior**
A clear and concise description of what you expected to happen.


: query_ptr(query_ptr_), context(context_)
{
}
BlockIO InterpreterAlterQuery::execute()
{
    BlockIO res;
    const auto & alter = query_ptr->as<ASTAlterQuery &>();
    if (!alter.cluster.empty())
        return executeDDLQueryOnCluster(query_ptr, context, getRequiredAccess());
    context.checkAccess(getRequiredAccess());
    auto table_id = context.resolveStorageID(alter, Context::ResolveOrdinary);
    StoragePtr table = DatabaseCatalog::instance().getTable(table_id, context);
    auto alter_lock = table->lockForAlter(context.getCurrentQueryId(), context.getSettingsRef().lock_acquire_timeout);
    auto metadata_snapshot = table->getInMemoryMetadataPtr();
    
    
    AddDefaultDatabaseVisitor visitor(table_id.getDatabaseName());
    ASTPtr command_list_ptr = alter.command_list->ptr();
    visitor.visit(command_list_ptr);
    AlterCommands alter_commands;