Revert "Validate search form of 404 page"

This reverts commit cd7d1246c23d35640a16de6153592c879471f963.
Fix- Search form in 404 will not search at all

Check used to look for main navigation tipue_search_input value.length which was empty.
On the other hand 404 search form has value in it.

This fix checks for the value of 404 search form separately.
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