Polishing
Always use testClass as declaringClass in the TCF

Prior to this commit, the following methods in ContextLoaderUtils
treated a composed annotation (i.e., a custom annotation that is
meta-annotated with test-related annotations) as the "declaring class"
instead of the actual test class that is either directly annotated with
the target annotation or meta-annotated with the target annotation. The
corresponding 'target' annotations are shown in brackets below.

- resolveContextConfigurationAttributes() [@ContextConfiguration]
- resolveContextHierarchyAttributes() [@ContextConfiguration]
- resolveActiveProfiles() [@ActiveProfiles]

This resulted in the following undesirable side effects:

(TODO: document side effects, the solutions, and new semantics)

Issue: SPR-11455