Limit columns selected in expression_is_true if failures not stored.

[elyobo]

Fixes #683

resolves #

This is a:

• documentation update
• bug fix with no breaking changes
• new functionality
• a breaking change

All pull requests from community contributors should target the main branch (default).

Description & motivation

As discussed in #683, the default behaviour for the expression_is_true test is to SELECT * which is expensive in some engines. The change instead does SELECT 1 unless should_store_failures() is true, resulting in faster and cheaper tests.

Checklist

• This code is associated with an Issue which has been triaged and accepted for development.
• I have verified that these changes work locally on the following warehouses (Note: it's okay if you do not have access to all warehouses, this helps us understand what has been covered)
  • BigQuery
  • Postgres
  • Redshift
  • Snowflake
• I followed guidelines to ensure that my changes will work on "non-core" adapters by: Not applicable
  • dispatching any new macro(s) so non-core adapters can also use them (e.g. the star() source)
  • using the limit_zero() macro in place of the literal string: limit 0
  • using dbt.type_* macros instead of explicit datatypes (e.g. dbt.type_timestamp() instead of TIMESTAMP
• I have updated the README.md (if applicable) Not applicable
• I have added tests & descriptions to my models (and macros if applicable) not sure if required, existing tests pass
• I have added an entry to CHANGELOG.md

[elyobo]

Tests not added, but existing tests pass; happy to add tests but not sure how to do so.

[joellabes]

Thanks @elyobo! Since this is changing the behaviour of the test, I've moved it to come out with the v1 release of dbt utils next month.

[elyobo]

Cool, thanks @joellabes, appreciate the merge.