Normalize is_iceberg Field for Consistency in Snowflake with QUOTED_IDENTIFIERS_IGNORE_CASE

[VersusFacit]

resolves #1227

Problem

In Snowflake, the QUOTED_IDENTIFIERS_IGNORE_CASE setting influences column names created by users, such as is_iceberg. However, this setting does not affect the column values returned by Snowflake’s SHOW OBJECTS query, creating inconsistency in how the is_iceberg field is referenced across different parts of the code.

When QUOTED_IDENTIFIERS_IGNORE_CASE is enabled, the is_iceberg column may appear in uppercase (IS_ICEBERG) in our homemade SHOW OBJECTS query, causing potential misalignment with the system table's always lowercase column names. This mismatch requires normalization to consistently refer to is_iceberg as a lowercase field name across Snowflake queries and Python processing, especially when working with adapters that handle Iceberg materializations.

Solution

Take 2: Removing quoting from the problem entirely and prove by hand that quoting in this metadata query doesn't matter one way or another.

I did so by hand and verified the test fails before the two fix lines are inserted.

just for fun, I did this with tdd: reproduce the failure/error, add the fix, go green!~~

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

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[mikealfare]

One sanity check, other wise it looks good. The failing CI is due to an expired token that we need to update.

I made a big chance to test things properly.

[adrianburusdbt]

@VersusFacit, there are a few other scenarios we need to consider as well, like this one: dbt-labs/dbt-core#4422
The way we handle QUOTED_IDENTIFIERS_IGNORE_CASE is again the culprit, so I think we should fix this issue throughout the adapter, not just for is_iceberg, i.e. normalize all column names.

[VersusFacit]

I tested this by manually place QUOTED_IDENTIFIERS_IGNORE_CASE = true and QUOTED_IDENTIFIERS_IGNORE_CASE = false and then verifying it didn't matter. This is a more predictable way to handle metadata query column names.

[mikealfare]

Two comments suggesting docstring updates, but these are non-blocking.