!temporary! Increase dotnet-install logging (#27972)
!temporary! Increase dotnet-install logging (#27972)

- changes may help figure out dotnet/core-eng#11424
- will likely go away in the next Arcade update PR
  - if not, we should revert this change after dotnet/core-eng#11424 is done for realz

FYI @MattGal I didn't find a way to add similar logging in tools.sh. Tried
- adding `chmod +x "$install_script"` in `GetDotNetInstallScript`
- changing commands to `bash "verbose=true \"$install_script\" ..."` in `InstallDotNet`
but that didn't get the `say_verbose` or `eval $invocation` bits in the script going.
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