Fix method names in CHANGELOG (#2570)

* Fix method names in CHANGELOG
* Delete reverted os_log Core CHANGELOG

Author: ryanwilson

Firebase/Core/CHANGELOG.md

@@ -1,11 +1,8 @@
 # 2019-03-19 -- v5.4.0 -- M45
 - [changed] Allow Bundle IDs that have a valid prefix to enable richer extension support. (#2515)
-- [changed] Convert FIRLogger to use the recommended os_log for logging via GoogleUtilities.
-  See https://developer.apple.com/documentation/os/logging?language=objc.
 - [changed] Deprecated `FIRAnalyticsConfiguration` API in favor of new methods on the Analytics SDK.
-  Please call the new APIs directly: Enable/disable Analytics with `Analytics.setAnalyticsEnabled(_)`
-  and modify the session timeout interval with `Analytics.setAnalyticsCollectionEnabled(_)`.
-
+  Please call the new APIs directly: Enable/disable Analytics with `Analytics.setAnalyticsCollectionEnabled(_)`
+  and modify the session timeout interval with `Analytics.setSessionTimeoutInterval(_)`.
 
 # 2019-01-22 -- v5.2.0 -- M41
 - [changed] Added a registerInternalLibrary API. Now other Firebase libraries register with FirebaseCore