Revert "Use BuildTools internally too" - internal builds now fail with `##[error]The remote provider was unable to process the request.`
Revert "Use BuildTools internally too"
- internal builds now fail with `##[error]The remote provider was unable to process the request.`

This reverts commit 0483e2db95d2c953a872f89ca438fec019f44787.

aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore