Release tranche of breaking changes (#4963)
* Remove deprecated `IJoinRoomOpts.syncRoom` option (#4914)
This option is non-functional, and was deprecated in
https://github.com/matrix-org/matrix-js-sdk/pull/4913. Remove it altogether.
* Remove support for `onlyData != true` (#4939)
* Remove deprecated fields, methods, utilities (#4959)
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Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Co-authored-by: Richard van der Hoff <richard@matrix.org>
