build: exclude tests from release package

[RabbiIslamRony]

PR Type

• Build related changes

Description

The release exclusion list currently includes the regression and WP-CLI smoke tests in the plugin package. Add /tests to .distignore so these developer scripts stay in the repository and are excluded from release packages that use this list.

Validation:

1. Compared rsync packaging dry runs using the original and updated .distignore: test paths were present before and absent after.
2. Confirmed both test scripts remain in the repository and the plugin entry point remains in the package file list.
3. git diff --check passed.

Any linked issues

Follow-up to the test-file discussion on #3018. Targets development so the packaging fix can be included in that release PR.

Checklist

• My code follows the WordPress coding standards (configuration-only change; no PHP changes).