Using Snowflake timestamp when casted can create issues while adding KPI

[suranah]

Describe the bug
Using Snowflake timestamp when cast from another column is creating issues while adding KPI.

Explain the environment

• Chaos Genius version: example is 0.1.2-alpha
• OS Version / Instance: TBA
• Deployment type: Docker

Current behavior
It returns an error dialog with the message - Error: 'timestamp column'. This is currently observed for a custom query.

Expected behavior
If the KPI definition follows all validation checks, it should be added as a KPI and subsequent analytics processed on it.

[kartikay-bagla]

This looks like an issue with query based KPIs only on Snowflake. We again tested it well with table based KPIs. This seems to be an issue with our metadata ingester. Will update on sometime for this.

[suranah]

@manassolanki do update on the fixes here for @gxu-kangaroo once you are done.

[manassolanki]

@gxu-kangaroo Snowflake metadata is case insensitive and snowflake DBAPI converts the metadata info to the uppercase. This is causing the issue while we are trying to match KPI definition (defined via metadata) with the query result. We have replaced the DBAPI cursor with the SqlAlchemy ResultProxy (which is wrapper around the DBAPI cursor to make things consistent across various DB/DW)