Inner repo builds should not double pass args

[mmitche]

The inner repo build command is based on the outer repo build command. Basically arcade is just taking the outer build command, adding a few new args, and then launching the new command. Duplicated args end up using the second value. This leads to some problems and some general awkwardness:

• Some args seem to ocassionally cause problems when passed twice. /bl: doesn't seem to override properly (at least in roslyn builds).
• It can be difficult to glance at a command line and identify what is going on.

T-Shirt Size: Small (probably not critical but ideal)

[mmitche]

Fit and finish item.

[Winniexu01]

This issue will be fixed in another way in the future: dotnet/arcade#15650 (comment)

[ellahathaway]

Reopening this issue since it'll be completed with #4249