[co19] Handle builders using co19 with test selectors

Previously, the script would look for an argument that is matches "co19"
exactly. NNBD builders currently use "co19/LanguageFeatures/nnbd" as a
test selector. This change will make the update script recognize both
the raw suite, as well as "suite with selectors".

Change-Id: I22d3274b7e99e4bfd96859bdb2ad47f4ff5acc37
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128721
Reviewed-by: William Hesse <whesse@google.com>

tests/co19/update.sh

@@ -49,7 +49,7 @@ BUILDERS=$(jq '.builder_configurations|
                 map(select(.steps|
                            any(.arguments|
                                select(.!=null)|
-                               any(.=="co19"))))|
+                               any(test("co19($|(/.*))")))))|
                 map(.builders)|
                 flatten|
                 sort' \