This fixes an issue that when changing for example the date, suddenly the log in screen is shown.
For example in a plugin I do
var tokenAuth = piwikUrl.getSearchParam('token_auth')
Which then sets indirectly
$search.token_auth='' which then results in
&token_auth=undefined in the URL. Meaning it will try to authenticate the user for the token
undefined which won't work. Also I think in general we should not append the URL accidentally ever to the URL in the browser.
getSearchParam() method should certainly not set a value indirectly here and it is a bug but not sure what side effects we would run into by removing the
search[paramName] = paramUrlValue;