Drop redundant <br> elements from tables in java.desktop HTML files

Many tables in componentProperties.html contain <br> element in the end of the cell. This element has no effect in this case, it can be removed safely without affecting the visual presentation of the tables.

The src/java.desktop/share/classes/javax/swing/plaf/synth/doc-files/componentProperties.html file has many tables with redundant <br> element in table cells.