fix(payments): hide paypal on paypal init failure

[StaberindeZA]

Because

• When the paypal button fails to load during initialization, for example when there is a PayPal sandbox outage, the subscription checkout page loads into an error, instead of hiding the PayPal button.
• This has resulted in a confusing user experience, as well as causing unrelated functional test failures due to the error page being shown.

This pull request

• If the PayPal button does not successfully finish it's onInit function, then hide the PayPal button instead of showing an error message.
• If any other PayPal error occurs, continue showing the error page.

Issue that this pull request solves

Closes: #FXA-9886

Checklist

Put an x in the boxes that apply

• [x] My commit is GPG signed.
• [x] If applicable, I have modified or added tests which pass locally.
• [x] I have added necessary documentation (if appropriate).
• [x] I have verified that my changes render correctly in RTL (if appropriate).

Other information (Optional)

The only way I found to replicate the failure scenario is to manually call the onError function before onInit completes.

Screenshots (Optional)

Please attach the screenshots of the changes made in case of change in user interface.