Use shared empty flag tests

[mikealfare]

resolves #1033

Problem

The local tests have been implemented in dbt-tests-adapter and these can get out of sync.

Solution

Swap out local test implementation to use the shared tests.

Implementation

1. Merge this PR demonstrating that these tests work
2. Move the bulk of this PR into dbt-tests-adapter
3. Create a final PR that removes most of this and uses the dbt-tests-adapter tests (we`re here)

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]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the dbt-snowflake contributing guide.

[github-actions]

The backport to 1.8.latest failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-1.8.latest 1.8.latest
# Navigate to the new working tree
cd .worktrees/backport-1.8.latest
# Create a new branch
git switch --create backport-1104-to-1.8.latest
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 8ae3ec89f7bc829cfa9351100905e13bc42542ac
# Push it to GitHub
git push --set-upstream origin backport-1104-to-1.8.latest
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-1.8.latest

Then, create a pull request where the base branch is 1.8.latest and the compare/head branch is backport-1104-to-1.8.latest.