[pkg:test_runner] Replace space from test config name
[pkg:test_runner] Replace space from test config name

https://dart-review.googlesource.com/c/sdk/+/181404 disallows spaces
in Configurations.

Change-Id: I0582eca064bd6d88ebcbbf411e44a6147895148c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/184902
Auto-Submit: Srujan Gaddam <4175f2f2dd3cde6c8ffb10fc9674dc09abf813fe@google.com>
Commit-Queue: William Hesse <a821cddceae7dc400f272e3cb1a72f400f9fed6d@google.com>
Reviewed-by: William Hesse <a821cddceae7dc400f272e3cb1a72f400f9fed6d@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk