remove changelog files

changelog.d/3830.feature

-Add option to track MAU stats (but not limit people)

changelog.d/3831.feature

-Add an option to enable recording IPs for appservice users

changelog.d/4165.bugfix

-Pushrules can now again be made with non-ASCII rule IDs.

changelog.d/4176.bugfix

-The media repository now no longer fails to decode UTF-8 filenames when downloading remote media.

changelog.d/4180.misc

-A coveragerc file, as well as the py36-coverage tox target, have been added.

changelog.d/4182.misc

-Add a GitHub pull request template and add multiple issue templates

changelog.d/4183.bugfix

-URL previews now correctly decode non-UTF-8 text if the header contains a `<meta http-equiv="Content-Type"` header.

changelog.d/4188.misc

-Update README to reflect the fact that #1491 is fixed

changelog.d/4189.misc

-Run the AS senders as background processes to fix warnings
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changelog.d/4190.misc

-Add some diagnostics to the tests to detect logcontext problems

changelog.d/4192.bugfix

-Fix an issue where public consent URLs had two slashes.

changelog.d/4193.misc

-Add missing `jpeg` package prerequisite for OpenBSD in README.

changelog.d/4197.bugfix

-Fallback auth now accepts the session parameter on Python 3.

changelog.d/4200.misc

-Add a note saying you need to manually reclaim disk space after using the Purge History API

changelog.d/4204.misc

-Fix logcontext leaks in EmailPusher and in tests
\ No newline at end of file

changelog.d/4205.misc

-More logcontext checking in unittests

changelog.d/4207.bugfix

-Remove riot.im from the list of trusted Identity Servers in the default configuration

changelog.d/4209.misc

-Fix logcontext leaks in EmailPusher and in tests
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changelog.d/4211.bugfix

-fix start up failure when mau_limit_reserved_threepids set and db is postgres 
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changelog.d/4214.misc

-Ignore __pycache__ directories in the database schema folder