The beatmap listing content swap-out logic was already a source of
several problems, and several attempts of fixing it were made. But as it
turns out it was terminally broken in several aspects.
* The `BypassAutoSizeAxes` juggling was finicky and ugly, and didn't
really look much different than an instant fade. Therefore, all fade
durations and manipulations of `BypassAutoSizeAxes` are removed.
* The transform sequence juggling the `BypassAutoSizeAxes` manipulations
was enqueued on the content which is being in the process of fading
out. That was partially fixed in 25e38560, but as it turns out, that
only works if `lastContent` is one of the two placeholder drawables
(results not found / supporter required to use filter).
It would not work if `lastContent` is a
`ReverseChildIDFillFlowContainer` with cards from a previous search in
it.
The `lastContent == foundContent` check, last touched in a49a4329, is
terminally broken, as it would always be false. `foundContent` is
mutated when a new card load task is started in `onSearchFinished()`,
which is *before* the aforementioned check.
The code prior to a49a4329 was checking against the two static reused
placeholder drawables which was the correct check to apply, and this
commit reverts to using a variant of that check.