fix: Disallow column aliases in inner queries of subqueries

[evanh]

When a column is aliased to something different in the inner subquery, it
breaks how aliasing works at the higher levels. It's also not necessary, since
the column can be referenced directly, and the outer query can alias the
expression however it likes in the results.

Also fixed some typing in the test file.

[codecov]

Test Failures Detected: Due to failing tests, we cannot provide coverage reports at this time.

❌ Failed Test Results:

Completed 315 tests with 1 failed, 313 passed and 1 skipped.

View the full list of failed tests

Test Description	Failure message
Testsuite: pytest Test name: tests.test_snql_api.TestSnQLApi::test_join_query_in_sub_query Envs: - default	Traceback (most recent call last): File ".../snuba/tests/test_snql_api.py", line 246, in test_join_query_in_sub_query assert response.status_code == 200 AssertionError: assert 400 == 200 + where 400 = <WrapperTestResponse 127 bytes [400 BAD REQUEST]>.status_code