Prior to this change, SpringApplication would register contexts to
SpringApplicationShutdownHook and only deregister them when they're
properly closed. A failed refresh attempt does not deregister the
context from the shutdown hook.
When a test suite runs lots of tests failing because of failed contexts,
this can build up and consume lots of resources.
This commit fixes this leak and deregisters failed contexts.
Fixes gh-29874
00114f9d61