Surface timeout environment variables to the admin panel

**Is your feature request related to a problem? Please describe.**
When wanting to configure or modify Metabase timeout settings, there's no way to do this in the UI currently. These environment variables can be set via the config file, but that is less convenient.

Some of the env vars that would be nice to surface:
- MB_DB_QUERY_TIMEOUT_MINUTES
- MB_DB_CONNECTION_TIMEOUT_MS

**Describe the solution you'd like**
Have these env vars be configurable in the admin panel, maybe on the databases tab.

**Describe alternatives you've considered**
Modifying these settings via the config file.

**Additional context**
Customer request

No files, tests, or entry points are mentioned. Start by tracing MB_DB_QUERY_TIMEOUT_MINUTES and MB_DB_CONNECTION_TIMEOUT_MS from configuration into the admin panel, including the proposed databases tab. Done means the requested timeout settings can be configured in the UI and their behavior is covered by appropriate tests.

Written by the indexing model from the issue text.