Fix mutually exclusive use of CachePut and Cacheable

Commit eea230f introduced a regression by adding a support for the
"result" variable in SpEL expression for @CachePut. As such expressions
cannot be evaluated upfront anymore, any method that contains both
@Cacheable and @CachePut annotations are always executed even when
their conditions are mutually exclusive.

This is an example of such mutual exclusion

@Cacheable(condition = "#p1", key = "#p0")
@CachePut(condition = "!#p1", key = "#p0")
public Object getFooById(Object id, boolean flag) { ... }

This commit updates CacheEvaluationContext to define a set of
unavailable variables. When such variable is accessed for a given
expression, an exception is thrown. This is used to restore the
evaluation of the @CachePut condition upfront by registering "result"
as an unavailable variable.

If all @CachePut operations have been excluded by this upfront check,
the @Cacheable operation is processed as it was before. Such upfront
check restore the behavior prior to eea230f.

Issue: SPR-11955