validate task never runs in default gulp workflow due to watchTask ordering

[Chaitu7032]

fixes - #5008

description

In the original gulpfile.js, the validate task was never executed in the default workflow.

This happened because validate was placed after watchTask inside a series().
Since watchTask starts a file watcher and never completes (by design), the series never reached validate.

This PR updates the task order and behavior so validation runs deterministically.

What was Changed

1] Moved validate to run before watchTask in the default task series
2] Updated watchTask to return the watch() call, making its long-running nature explicit to Gulp

Why This Change needed ?

1] Ensures validate runs at least once during the default workflow
2] Prevents silent skipping of validation
3] Aligns task structure with Gulp’s recommended lifecycle handling for long-running tasks
4] Improves developer feedback without changing build or watch behavior

How to test

1] Run the default task:

gulp

Confirm that:
1] validate runs before watch mode starts
2] The watcher continues running as expected after validation

Impact

1] No breaking changes
2] No behavior change to watch mode
3] Improves correctness and reliability of the default workflow.

screenshots

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.