[TrimmableTypeMap] Stabilize CoreCLR Mono.Android.NET-Tests lane

[simonrozsival]

Summary

• run Mono.Android.NET-Tests with _AndroidTypeMapImplementation=trimmable and UseMonoRuntime=false on CoreCLR
• add/update the dedicated CoreCLRTrimmable lane coverage for this scenario
• fix the main runtime/build blockers so the test app builds, installs, starts, and completes instrumentation successfully
• keep the remaining gaps explicit via temporary exclusions for unsupported or separately tracked buckets

Main fixes in this PR

• build/target ordering and incremental invalidation when switching between llvm-ir and trimmable
• trimmable runtime bootstrap hardening for typemap lookup, proxy resolution, and registerNatives() hookup
• open-generic proxy emission fixes in the trimmable typemap generator
• JNIEnv.NewObjectArray<Type>() / non-IJavaPeerable fallback to java/lang/Object
• NUnitInstrumentation updates for the current temporary exclusions

Current validation state

The local device lane now finishes green with the current exclusions:

passed=769
skipped=6
failed=0
run=775

Temporary exclusions / follow-up work

The remaining excluded buckets are intentional and should be handled in follow-up work (tracked separately, e.g. #11099):

• Export
• GCBridge / DoNotLeakWeakReferences
• Java.Interop helper/proxy scenarios such as JavaPeerableExtensionsTests.JavaAs*
• existing NativeTypeMap, SSL, TrimmableIgnore, and CoreCLRIgnore buckets that still need parity work

Local usage

./dotnet-local.sh build -t:RunTestApp tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj \
  -p:_AndroidTypeMapImplementation=trimmable \
  -p:UseMonoRuntime=false