Remove some streams from rtc_base/

Bug: webrtc:8982
Change-Id: Id372dde980fae493debf20873b6aeee8a7f1b045
Reviewed-on: https://webrtc-review.googlesource.com/78781
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23396}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index a35a89c..96822ca 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -654,6 +654,7 @@
 }
 
 rtc_source_set("rtc_json") {
+  testonly = true
   defines = []
   sources = [
     "json.cc",