[Fix] Redo-LTService Prompt Issue

[Kamalgurna]

Made sure 'Uninstall.exe', 'Uninstall.exe.config' are not present before running Agent_unnstall.exe
As it was the reason for the prompts, Agent_unnstall.exe was prompting to replace these files in the directory
-Added progresspreference as .net 3 installation was waking alots of time to get installed on some machines.