[BUGFIX] Ensure IRRE record selectors show up with maxitems set

When an IRRE field in FormEngine has maxitems set,
and an item gets removed (thus, allowing an inline element
to be added again), the buttons to create new elements
are shown again.

This fixes a regression introduced with #91595.

Resolves: #93091
Resolves: #93238
Related: #91595
Releases: master, 10.4
Change-Id: If4c8152ab6e4fc1388fbfcf1af72fa2609f6df16
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67542
Tested-by: Jörn Wagner <joern.wagner@explicatis.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Jörn Wagner <joern.wagner@explicatis.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>

Build/Sources/TypeScript/backend/Resources/Public/TypeScript/FormEngine/Container/InlineControlContainer.ts

@@ -794,7 +794,7 @@ class InlineControlContainer {
    */
   private toggleContainerControls(visible: boolean): void {
     const controlContainer = this.container.querySelector(Selectors.controlContainer);
-    const controlContainerButtons = controlContainer.querySelectorAll('a');
+    const controlContainerButtons = controlContainer.querySelectorAll('button, a');
     controlContainerButtons.forEach((button: HTMLElement): void => {
       button.style.display = visible ? null : 'none';
     });