dbt-glue fails to find source table in Glue when TableType key not present

### Describe the bug
When a source glue table does not contain the "TableType" key, dbt-glue throws an error when attempting to connect to it:

```
AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: Unable to fetch table . TableType cannot be null for table:
```

### Steps To Reproduce
1. Create a table in Glue without the TableType key. I am not sure if this can be done manually; however, AWS AppFlow currently leaves out the TableType key when it creates Glue tables.
2. Set this table as a source in dbt
3. call dbt run

### Expected behavior
Glue tables without a TableType key work in Glue, so the adaptor should fall back to some default when this key is not present. For example, the default could be "EXTERNAL_TABLE".

### System information
**The output of `dbt --version`:**
```
Core:
- installed: 1.9.3
- latest: 1.9.3 - Up to date!

Plugins:
- glue: 1.9.2 - Up to date!
- spark: 1.9.2 - Up to date!
```

Windows 11, 64bit

Python 3.13.1

Start by reproducing the failure with dbt run using an AWS Glue source table created without the TableType key, then trace the dbt-glue adapter's source-table handling. Done means the adapter can connect to such a Glue table without the reported TableType cannot be null error; no specific file or test is named in the issue.

Written by the indexing model from the issue text.