Travis CI: Remove sudo usage while building

[smitpatel]

With #8749 , we are moving to sudo: required on travis build.

Investigating into issue while travis fails with

MSBUILD : error MSB4166: Child node "19" exited prematurely. Shutting down. Diagnostic information may be found in files in the temporary files directory named MSBuild_*.failure.txt.

1. Trying to reproducing using docker image of travis did not help much. It was able to build. Though it had more than 100% CPU usage and hardly any RAM left from 2GB available memory. Also it did not utilize any swap memory.
2. Trying to mimic the environment travis have in local Ubuntu VM, it still passes. But when dropping RAM to 512MB, it hangs. MSBuild is certainly having issues with low memory available.

There are few related issues
dotnet/msbuild#2168 - this one talks about high memory usage in MSBuild.

dotnet/msbuild#2164 - is the issue we have filed about travis build.

At present, by enabling sudo which gives us higher machine specs, we have got build passing.
Ideally we should not need sudo usage. We can safely remove it once MSBuild figures out & resolves the underlying issue.

[smitpatel]

2ba1dc0 removed sudo usage for testing.