Previously, the auto-configuration of DevTools’ debug, restart, and
health handlers assumed that the server was running on its default
context path and, if server.context-path was set to a non-default value,
the handlers would not work as expected.

This commit updates the auto-configuration of the three handlers to 
consider the server’s context path when configuring their URIs. Now,
when a custom server context path is used, no further configuration is
required other than the inclusion of that context path when providing
the remote URL as an argument to RemoteSpringApplication.

Closes gh-4301