This commit improves said method to ensure that user is redirected to
the right page before returning.
### Reviewer notes
Example of test flakiness:
https://github.com/discourse/discourse/actions/runs/14081653020/job/39435797236
```
Failure/Error: raise capybara_timeout_error
CapybaraTimeoutExtension::CapybaraTimedOut:
This spec passed, but capybara waited for the full wait duration (10s) at least once. This will slow down the test suite. Beware of negating the result of selenium's RSpec matchers.
[Screenshot Image]: /__w/discourse/discourse/tmp/capybara/failures_r_spec_example_groups_user_resetting_password_when_desktop_when_user_has_multi_factor_authentication_configured_when_user_has_security_key_and_backup_codes_configured_should_allow_a_user_to_reset_pass_261.png
~~~~~~~ JS LOGS ~~~~~~~
~~~~~ END JS LOGS ~~~~~
Shared Example Group: "forgot password scenarios" called from ./spec/system/forgot_password_spec.rb:213
./spec/rails_helper.rb:426:in `block (3 levels) in <top (required)>'
./spec/rails_helper.rb:619:in `block (3 levels) in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/benchmark-0.4.0/lib/benchmark.rb:304:in `measure'
./spec/rails_helper.rb:619:in `block (2 levels) in <top (required)>'
./spec/rails_helper.rb:580:in `block (3 levels) in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/timeout-0.4.3/lib/timeout.rb:185:in `block in timeout'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/timeout-0.4.3/lib/timeout.rb:192:in `timeout'
./spec/rails_helper.rb:570:in `block (2 levels) in <top (required)>'
./spec/rails_helper.rb:527:in `block (2 levels) in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/webmock-3.25.1/lib/webmock/rspec.rb:39:in `block (2 levels) in <top (required)>'
```
This commit adds a loading state to the confirm button in
`confirm-session` dialog.
This also unskips the flaky system tests in
`spec/system/forgot_password_spec.rb` as this change will allow us to
gather more information about why the test is flaky. The screenshots
which we have gathered when the test flakes does not allow us to know if
the button has been clicked or not before the test times out.
This switches the signup/login UI to the full page experience by
default. This has been in use by many sites for multiple months and we
have ironed out many fixes in the meantime.
The `full_page_login` setting is also marked for removal in about
1.5mths, by the end of April 2025.
This commit fixes a problem where the user will not be able to reset
their password when they only have security keys and backup codes
configured.
This commit also makes the following changes/fixes:
1. Splits password reset system tests to
`spec/system/forgot_password_spec.rb` instead of missing the system
tests in `spec/system/login_spec.rb` which is mainly used to test
the login flow.
2. Fixes a UX issue where the `Use backup codes` or `Use authenticator
app` text is shown on the reset password form when the user does
not have either backup codes or an authenticator app configured.
