Ensure that all servlet containers handle servlet startup failures
consistently and throw a `WebServerException` that wraps the original
cause.
Both Undertow and Jetty already dealt with startup failures in this
way, but Tomcat did not. The `TomcatEmbeddedContext` has now been
changed to no longer call `super.loadOnStartup` but instead re-implement
a version of that method that wraps and rethrows the original exception
(as long as `failCtxIfServletStartFails` is `true`, which it now is by
default).
Closes gh-14790
683e9532d6