[imorland]

Related to flarum/framework#4665 ([1.x & 2.x] Permanent Ban suspended_until is set to 2038-01-01 00:00:00).

Changes proposed in this pull request:
Clarify that reopening an indefinite suspension keeps Suspended indefinitely selected. This accompanies the 2.x recognition fix.

Reviewers should focus on:

• The instructions for changing or lifting a suspension.

Necessity

• Has the problem that is being solved here been clearly explained?
• If applicable, have various options for solving this problem been considered?
• For core PRs, does this need to be in core, or could it be in an extension?
• Are we willing to maintain this for years / potentially forever?

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Frontend changes: tests are green (run yarn test in js/).
• Frontend changes: tests have been added, or are not appropriate here.
• Backend changes: tests are green (run composer test).
• Backend changes: tests have been added, or are not appropriate here.
• Where applicable, changes are suitable for all supported database drivers (MySQL, MariaDB, PostgreSQL, SQLite).
• Core developer confirmed locally this works as intended.
• The description above is written by me and describes what this pull request actually does.

Required changes:

• Related implementation PR: [2.x] fix(suspend): recognise indefinite suspensions consistently framework#5437 ([2.x] fix(suspend): recognise indefinite suspensions consistently)