Clean up code that became redundant through framework changes

Clean up code that became redundant through framework changes

There were two changes in framework that triggered this commit:
KHamburgerMenu and KToolTipHelper.

When the Dolphin-specific hamburger menu was replaced by
KHamburgerMenu, I didn't clean everything up correctly. Not
anymore!

Help texts also weren't updated accordingly. This commit replaces
any mention of the old hamburger menu which was called "Control"
with text that reflects the current application state.

The other framework change "KToolTipHelper" takes responsibility
for opening links in help texts. So we won't need code to do this
in Dolphin anymore. This means we can also get rid of some
duplicate help texts which only existed because links didn't work
correctly in some places.