[ddc] Hot reload test suite result names need to be cleaned up

[nshahan]

The ddc hot reload test suite is reporting names that are inconsistent with the rest of the test suites. This makes the results difficult to query for in the results databases or the current results web UI.

The diff verification creates results like this:

tests/reload//b/s/w/ir/cache/builder/sdk/tests/hot_reload/const_to_non_const_class/main.0.dart-diff
tests/reload//b/s/w/ir/cache/builder/sdk/tests/hot_reload/const_to_non_const_class/main.1.dart-diff

• The beginning of the path should start with the suite name hot_reload to be consistent with other test suites.

The overall test results (not the diff verification) is reported like this:

tests/reload/const_to_non_const_class

• The beginning of the path should start with the suite name hot_reload to be consistent with other test suites.