Don't break core's parserTests if VisualEditor is installed

VisualEditor's hook changes the edit section link, which changes the
output of certain parser tests so that they no longer match the
expected text.  Use the `ParserTestsGlobal` hook (which cleans up
after itself when the parserTests ends) to disable the
`onDoEditSectionLink` hook when we're running parserTests to avoid
the spurious failures.

Change-Id: Ic958d88f443ac37ba304d3256e2bb5ea2fde820d
Merge "Don't break core's parserTests if VisualEditor is installed"