Trimming defaults don't use advised trimming behavior

[breyed]

Trimming defaults vary by build configuration:

By default, Android and Mac Catalyst builds use partial trimming when the build configuration is set to a release build.

However, the trimming behavior advice says not to:

The $(TrimMode) build property shouldn't be conditioned by build configuration.

Either the behavior should be changed to match the advice or the advice should be updated to indicate when it is and is not recommended to condition TrimMode by configuration.

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Associated WorkItem - 350513