Enable trim/AOT analysis on libraries test projects

I'm getting tired of fixing native AOT outerloops every time someone checks in an untrimmable libs test (#126854 and #126817 just in the last 24 hours). We should enable the AOT/trim analyzer on all test projects so that it's a build break (with WarnAsError) for whoever tries to add such thing.

I'm working on a change that enables this on everything and then selectively disables it for test projects that have warnings. Then I'll let copilot remove the disabling project by project to get us clean and stay clean. I need an issue number for this effort, so this is the issue.