nz-tree-select: no search or dropdown arrow icons

[FrankSmithAdder]

Reproduction link

https://stackblitz.com/edit/ng-zorro-antd-ivy-7akl8xab?file=src%2Fapp%2Fapp.component.ts

Steps to reproduce

• set the nzMultiple flag for nz-tree-select to true.
• Note that the values for nzAllowClear and nzShowSearch no longer have the expected behaviours - the icons for them are no longer shown.

What is expected?

• nz-tree-select does not display the dropdown and search icons, when the nzMultiple flag is set to true. It should still show these icons.

What is actually happening?

the dropdown and search icons are not shown when nzMultiple is set to true

Environment	Info
ng-zorro-antd	20.1.2
Browser	chrome

[keke521jie]

It seems the icon is intentionally hidden when nzMultiple is set, according to the code snippet.

   @if (!isMultiple || (hasFeedback && !!status)) {
        <nz-select-arrow [showArrow]="!isMultiple" [feedbackIcon]="feedbackIconTpl">
          <ng-template #feedbackIconTpl>
            @if (hasFeedback && !!status) {
              <nz-form-item-feedback-icon [status]="status"></nz-form-item-feedback-icon>
            }
          </ng-template>
        </nz-select-arrow>
      }

[FrankSmithAdder]

@Laffery Yes, though I'm not sure why we would want this; IMO removing the !isMultiple condition as part of this logic is most correct.

In particular, note that when its in single select mode, clearing is possible, but it's even more so when there are multiple inputted values from nz-multiple-select - otherwise users need to click the x on every selected tag to remove them all.

This may also require some additional logic to clear out the inputted tags, which might be why the check for !isMultiple was added in the first place.

[Laffery]

@Laffery Yes, though I'm not sure why we would want this; IMO removing the !isMultiple condition as part of this logic is most correct.

In particular, note that when its in single select mode, clearing is possible, but it's even more so when there are multiple inputted values from nz-multiple-select - otherwise users need to click the x on every selected tag to remove them all.

This may also require some additional logic to clear out the inputted tags, which might be why the check for !isMultiple was added in the first place.

We will support it in v20.2 via #9328