Credentials can be viewed by anyone with macro

**Is your feature request related to a problem? Please describe.**
I poked around and found out that credentials can be easily viewed with macro

```sql
{{ adapter.get_credentials({}) }}
```
This method appeared in commit https://github.com/ClickHouse/dbt-clickhouse/commit/24af7d94d4a3bd46686490838257aaab134ac2b1
It is used for dictionary materialization, and.. it makes impossible to work on project with team securely, cause anyone can paste production account somewhere.

**Describe the solution you'd like**
It should not exist

Start by inspecting commit 24af7d94d4a3bd46686490838257aaab134ac2b1 and searching the repository for adapter.get_credentials and dictionary materialization. Confirm where credentials become available to macros, then define a regression check showing that macros cannot view them while dictionary materialization continues to work.

Written by the indexing model from the issue text.