Update `StandardConfigDataLocationResolver` so that profile-specific
imports can only be used when there is no parent import.
Prior to this commit, given the following application.properties file:
spring.profiles.active=p1,p2
spring.config.import=other.properties
We would attempt to import `other.properties`, `other-p1.properties`
and `other-p2.properties`. This seems quite confusing and when we really
only need to support profile-specific properties for the initial root
set of locations.
Fixes gh-26752
d1b256a169