Clean up test_runner and the test matrix to remove all references to
the service test suite and delete the tests.

Work towards https://github.com/dart-lang/sdk/issues/50233

TEST=N/A

Change-Id: Ie3adb0d007d71f9a223843d739e57cbdb5be0d59
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429140


Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Ivan Inozemtsev <iinozemtsev@google.com>