[mobile] Replace `<TrimMode>link</TrimMode>` in mobile targets

[matouskozak]

We currently use <TrimMode>link</TrimMode> in many mobile (Android/Apple) target/rpoject files while the officially supported options are full and partial (https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/trimming-options#trimming-granularity). The default SDK TrimMode is full.

Android usage:

• runtime/src/mono/msbuild/android/build/AndroidBuild.InTree.props

  Line 10 in 1587221

  <TrimMode>link</TrimMode>

• runtime/src/mono/sample/Android/AndroidSampleApp.csproj

  Line 9 in 1587221

  <TrimMode>Link</TrimMode>

Apple usage:

• runtime/src/mono/sample/iOS/Program.csproj

  Line 15 in 1587221

  <TrimMode>Link</TrimMode>

• runtime/src/mono/msbuild/apple/build/AppleBuild.InTree.props

  Line 10 in 1587221

  <TrimMode>link</TrimMode>

• runtime/src/mono/msbuild/apple/build/AppleBuild.LocalBuild.targets

  Line 29 in 1587221

  <TrimMode>link</TrimMode>

Test:

• runtime/eng/testing/tests.mobile.targets

  Line 98 in 1587221

  <TrimMode>link</TrimMode>

[dotnet-policy-service]

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