Use in-memory output instead of file in RTC event log test.

Bug: webrtc:13670
Change-Id: I17bf1dbc29b8e8ebfd019f213c4ae1e24a91d356
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251520
Reviewed-by: Markus Handell <handellm@webrtc.org>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35974}
diff --git a/logging/BUILD.gn b/logging/BUILD.gn
index f2385be..d167953 100644
--- a/logging/BUILD.gn
+++ b/logging/BUILD.gn
@@ -490,6 +490,7 @@
         "../system_wrappers",
         "../test:fileutils",
         "../test:test_support",
+        "../test/logging:log_writer",
         "//testing/gtest",
       ]
       absl_deps = [