What is the problem?
This is a follow up to 4cca7de22d. In the
commit, CSS was used to disable the collapsing of sections in the header
dropdown navigation menu when the `navigation_menu` site setting is set
to `header dropdown`. However, using CSS is not the correct approach as
the underlying code is still marking the section as collapsable which
means that the sections will still be displayed as collapsed with no way
to "uncollapse" if the local store has already marked the section as
collapsed.
What is the fix?
This commit removes the usage of CSS to hide the collapsabe button and
instead correctly marks the section as not collapsable in the code.
c991b8f6a0