Stripe Checkout Offsite Flow does not automatically create the site after checkout

[MaryOJob]

Describe the bug When the payment flow to checkout offsite is selected with the Stripe gateway, the site details despite being filled at checkout do not automatically create the site the member has paid for. They need to manually go to the "Manage Sites" page to again fill in their site details to create the site they have paid for.

Steps to reproduce the behavior:

1. Activate PMPro on a Multisite
2. Activate the Member Network Sites Add On
3. Generate the Manage Sites page and edit any membership level to include the number of sites a member gets
4. On the PMPro Gateway Settings page, set Stripe payment flow to happen offsite on Stripe
5. Complete a checkout on the level, fill in the site details, name and title
6. See the issue, the site is not automatically created after checkout
7. Note that the site is created on the network list of sites but not linked to the user who checked out offsite at Stripe, creating the site on the "Manage Sites" page after checkout however creates another site and links it to the user correctly

Screenshots If applicable, please attach a screenshot to make your issue clearer.

Expected behavior As with the Stripe onsite checkout where the site gets automatically created, the same is expected to occur when the checkout flow is set to Stripe offsite as well.

Isolating the problem (mark completed items with an [x]):

• [x] I have deactivated other plugins and confirmed this bug occurs when only Paid Memberships Pro plugin and Member Network Sites Add On is active.
• [x] This bug happens with a default WordPress theme active, or Memberlite.
• [x] I can reproduce this bug consistently using the steps above.

WordPress Environment

``` - WordPress version 6.6.1 - PHP version 8.0.30 - Paid Memberships Pro Version 3.1.2 - Member Network Sites Version 0.5.4

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[MaryOJob]

Moderators Only: #585320

[ipokkel]

Moderators Only: #643635