Remove dead special-casing for OLM.BAD_LEGACY_ACCOUNT_PICKLE
We used to show a special error message when we got this error; however
https://github.com/matrix-org/matrix-react-sdk/pull/783 made that not work.
You'll only hit it if you're upgrading from some ancient version of Olm, and
I'm quite happy for us to fall back to the generic 'couldn't restore: vape your
storage?' flow in that case. (In any case that's preferable to dumping you at
the login prompt with no warning that we've just vaped your storage).
matrix-react-sdk
efc5cf28 - Remove dead special-casing for OLM.BAD_LEGACY_ACCOUNT_PICKLE
