Correct the check whether .htaccess update is required

[SergeyBiryukov]

Background: #39547

[27549] / #19268 introduced a check whether .htaccess update is required after saving permalink settings, so that "You should update your .htaccess file now" message is only displayed when necessary.

As part of the changes in [37747] / #35936 and [38066] / #37380, some logic was reshuffled, and the check is now performed before the permalink structure is updated, leading to the message not being displayed as intended, due to outdated values being compared.

The check should be performed after the permalink structure update, not before.

[SergeyBiryukov]

In 48710:

Permalinks: Correct the check whether .htaccess update is required when saving permalink settings.

The check should be performed after the permalink structure update, not before.

Fixes #50834.

[SergeyBiryukov]

In 48712:

Permalinks: Simplify the logic for displaying "You should update your .htaccess file now" message.

See #39547, #50834.