CompositeReactiveHealthIndicatorTests.timeoutReachedUsesFallback is flaky on Windows

[wilkinsona]

This relates to reactor/reactor-core#2297. With thanks to @SBasle and @bsideup for the analysis, it appears that the precision of Windows' timer degrades significantly under load such that a 100ms timeout may be missed. The recommendation is to stabilise the test be increasing the timeout and delay periods to reduce the likelihood of them being less than Windows' timing precision.