remove various broken build status tags

Author: fowles

README.md

@@ -1,8 +1,6 @@
 Protocol Buffers - Google's data interchange format
 ===================================================
 
-[![Build status](https://storage.googleapis.com/protobuf-kokoro-results/status-badge/linux-javascript.png)](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fubuntu%2Fjavascript%2Fcontinuous) [![Build status](https://storage.googleapis.com/protobuf-kokoro-results/status-badge/macos-javascript.png)](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fmacos%2Fjavascript%2Fcontinuous)
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 Copyright 2008 Google Inc.
 
 This directory contains the JavaScript Protocol Buffers runtime library.