Revert "Revert "LPS-35804 PanelTag should clean up attributes on doEndTag""

This reverts commit 0c65ffd745f070fbc793e4020c2dbe67e43207ac.
Revert "Revert "LPS-35804 Set extended to null on clean up""

This reverts commit fff1d3466ef060f79b5b97e4f0ad8a9a24e9c7a0.
LPS-35804 Keep PanelContainerTag clean up for extended attribute like it was before
LPS-35804 Panel extended attribute can be null and if specified should overwrite the value of panel container extended attrribute