QTest::qWaitFor(., int): remove superfluous static keyword

The static keyword prevents the linker from reusing the executable
code of one TU's instantiation of this function in other TUs.

There's no reason for this restriction, so remove it.

Amends 292cb12e02.

Pick-to: 6.7
Change-Id: Ide60ce0bf4b7118295fad98a25bd438fc1da2039
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/kernel/qtestsupport_core.h

@@ -52,7 +52,7 @@ qWaitFor(Functor predicate, QDeadlineTimer deadline = QDeadlineTimer(std::chrono
 }
 
 template <typename Functor>
-[[nodiscard]] static bool qWaitFor(Functor predicate, int timeout)
+[[nodiscard]] bool qWaitFor(Functor predicate, int timeout)
 {
     return qWaitFor(predicate, QDeadlineTimer{timeout, Qt::PreciseTimer});
 }