streamproducer: remove loop from eventStream

This switches eventStream to just do its work on the rangefeed client callback
handlers directly, without an extra channel handoff and loop with its own
duplicate frontier.

Release note: none.
Epic: none.

pkg/ccl/streamingccl/streamproducer/BUILD.bazel

@@ -22,7 +22,6 @@ go_library(
         "//pkg/jobs/jobsprotectedts",
         "//pkg/keys",
         "//pkg/kv",
-        "//pkg/kv/kvclient/kvcoord",
         "//pkg/kv/kvclient/rangefeed",
         "//pkg/kv/kvclient/rangefeed/rangefeedcache",
         "//pkg/kv/kvpb",
@@ -58,11 +57,11 @@ go_library(
         "//pkg/util/mon",
         "//pkg/util/protoutil",
         "//pkg/util/span",
+        "//pkg/util/syncutil",
         "//pkg/util/timeutil",
         "//pkg/util/tracing",
         "//pkg/util/uuid",
         "@com_github_cockroachdb_errors//:errors",
-        "@com_github_cockroachdb_logtags//:logtags",
     ],
 )