Run singular tests conditionally

[amishas157]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with the jira ticket associated with the PR.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated the docs and README with the added features, breaking changes, new instructions on how to use the repository.

Release planning

• I've decided if this PR requires a new major/minor/patch version accordingly to
  semver, and I've changed the name of the BRANCH to release/* , feature/* or patch/* .

What

This PR adds config in singular tests to be enabled only in prod environment and when variable is_singular_airflow_task setup.

Why

It is a known problem that singular tests run whenever dbt build command is executed. Even with adding --exclude singular_test argument, dbt does not stop running these tests. Ideally we want singular tests to be run only as part of dbt_singular_tests airflow task.

The other option was to:

• Run dbt run and then dbt test --exclude singular_test. However, that will create data and then run tests , which introduces risk of bad data quality.

Testing

Enriched_base_table_task does not run any singular test with this PR

dbt_singular_test_task runs only ledger_sequence_increment test since that enabled for test environment. In prod env, all singular test should run okay

[sydneynotthecity]

LGTM