Refactor useAddSite reset form and simplify the state

[sejas]

Related issues

• Follow up:
  • Refactor blueprint deeplink handling in the Add site modal #2216
  • Clean setSelectedRemoteSite when closing modal #2230

Proposed Changes

• This PR is a refactor; it does not add new functionality or fix any issues.
• It refactors how we reset the Add Site form after closing the modal or creating a site.
• Removes the unnecessary localAddSiteProps variable.
• Clean sites and loadingSites from useAddSite. These values should be consumed directly from useSiteDetails.
• It doesn't reset the form in NoStudioSites because that component will reset its state when it gets unmounted.

Testing Instructions

• Run npm start
• Click on Add site
• Try each option
• Confirm there are no regressions and that the creation of one site doesn't affect another. For example, after pulling an existing site, creating a blank site should result in just a blank site being created.
• Repeat the testing but this time remove all your local sites to try the site creation without the modal.
• Try to open blueprint deeplinks, e.g.:

wp-studio://add-site?blueprint=eyJtZXRhIjp7InRpdGxlIjoiVGhpcyBpcyBhIHRlc3QgYmx1ZXByaW50IiwiZGVzY3JpcHRpb24iOiJJdCBpbnN0YWxscyBBc3RyYSB0aGVtZSBhbmQgWW9hc3QgU0VPIHBsdWdpbiIsImF1dGhvciI6Iml2YW4iLCJjYXRlZ29yaWVzIjpbInJzcyIsInNvY2lhbCB3ZWIiXX0sInByZWZlcnJlZFZlcnNpb25zIjp7InBocCI6IjguMyIsIndwIjoibGF0ZXN0In0sInN0ZXBzIjpbeyJzdGVwIjoiaW5zdGFsbFRoZW1lIiwidGhlbWVEYXRhIjp7InJlc291cmNlIjoid29yZHByZXNzLm9yZy90aGVtZXMiLCJzbHVnIjoiYXN0cmEifSwib3B0aW9ucyI6eyJhY3RpdmF0ZSI6dHJ1ZX19LHsic3RlcCI6Imluc3RhbGxQbHVnaW4iLCJwbHVnaW5EYXRhIjp7InJlc291cmNlIjoid29yZHByZXNzLm9yZy9wbHVnaW5zIiwic2x1ZyI6IndvcmRwcmVzcy1zZW8ifSwib3B0aW9ucyI6eyJhY3RpdmF0ZSI6dHJ1ZX19LHsic3RlcCI6ImxvZ2luIiwidXNlcm5hbWUiOiJhZG1pbiIsInBhc3N3b3JkIjoicGFzc3dvcmQifV19 

or the ones in https://jsbin.com/levaburate/2/edit?html,css,output .

3. Confirm there are no unexpected behavior, and all sites should be created correctly.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[ivan-ottinger]

Nice clean-up, Antonio! 54 more lines gone! 👍🏼

The changes look good and I did not observe any regressions (tested all options with existing local sites and with no sites as well). The form gets cleared correctly. The blueprint deeplinks still work as before. 👌🏼

[github-actions]

📊 Performance Test Results

Comparing 3d8ea42 vs trunk

site-editor

Metric	trunk	3d8ea42	Diff	Change
load	26137.00 ms	19625.00 ms	-6512.00 ms	🟢 -24.9%

site-startup

Metric	trunk	3d8ea42	Diff	Change
siteCreation	42209.00 ms	23893.00 ms	-18316.00 ms	🟢 -43.4%
siteStartup	14268.00 ms	14213.00 ms	-55.00 ms	🟢 -0.4%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change

[katinthehatsite]

This seems to work as expected for me 👍 I did not spot any further regressions