remove loader depth warning, replace with logging message

remove loader depth warning, replace with logging message

Replaced the "loader depth is excessively deep" warning with a shorter
message added to the caching badge within SQL logging, for those statements
where the ORM disabled the cache due to a too-deep chain of loader options.
The condition which this warning highlights is difficult to resolve and is
generally just a limitation in the ORM's application of SQL caching. A
future feature may include the ability to tune the threshold where caching
is disabled, but for now the warning will no longer be a nuisance.

Fixes: #10896
Change-Id: Ic3be2086d1db16f9a75390323f00a43ef72aca12