fix(macros): resolve_template fails in audits when this_model is a subquery

[sravankumarkunadi]

Description

@resolve_template raises AttributeError: 'Subquery' object has no attribute 'catalog' in an audit attached to a model with a time_column (so, any INCREMENTAL_BY_TIME_RANGE model).

The macro assumes @this_model is a table and calls .catalog / .db / .name on it. But Model.render_audit_query only passes a table when there's no time filter — otherwise it passes a subquery restricting the physical table to the audited range:

"this_model": exp.select("*").from_(quoted_model_name).where(where).subquery()
if where is not None
else quoted_model_name,

exp.to_table() returns non-Table expressions untouched, so the Subquery reaches .catalog and raises. #3991 fixed the where is None branch; the time-column branch still produces the subquery.

This unwraps the subquery to the table it selects from before resolving the template. @this_model is unchanged — audits still get the time-filtered subquery — only the catalog/schema/table lookup reaches through it, which is what those placeholders mean. That makes mode := 'table' usable in audits that need the full materialized table rather than the current batch.

Closes #5927

Test Plan

• test_resolve_template_subquery (test_macros.py) — mode := 'table' with a subquery this_model; fails on main with the reported AttributeError.
• test_resolve_template (test_audit.py) — end to end through render_audit_query on an incremental model, both modes; the literal case also asserts @this_model still renders as the time-filtered subquery.
• pytest tests/core/test_macros.py tests/core/test_audit.py tests/core/test_model.py -m "not slow and not docker" → 487 passed vs 485 on main (the 2 new tests). Both runs hit the same 27 errors, all ConfigError: Materialization strategy ... was not found — test fixture entry points missing from my venv, none in the two files touched here.
• make style clean on the changed files.

Checklist

• I have run make style and fixed any issues
• I have added tests for my changes (if applicable)
• All existing tests pass (make fast-test) — ran the three files above rather than the full suite, see the pre-existing local errors noted there
• My commits are signed off (git commit -s) per the DCO