Disable character range check for user IDs

[neilalexander]

This check is not safe in existing room versions because Synapse hasn't enforced it properly either.

Related: matrix-org/matrix-spec#1506, matrix-org/matrix-spec-proposals#2828

Signed-off-by: Neil Alexander git@neilalexander.dev

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.09% :tada:

Comparison is base (c48e302) 58.37% compared to head (ac984c7) 58.47%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #410 +/- ## ========================================== + Coverage 58.37% 58.47% +0.09% ========================================== Files 51 51 Lines 7023 7032 +9 ========================================== + Hits 4100 4112 +12 + Misses 2533 2531 -2 + Partials 390 389 -1 ``` | [Files Changed](https://app.codecov.io/gh/matrix-org/gomatrixserverlib/pull/410?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=matrix-org) | Coverage Δ | | |---|---|---| | [spec/userid.go](https://app.codecov.io/gh/matrix-org/gomatrixserverlib/pull/410?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=matrix-org#diff-c3BlYy91c2VyaWQuZ28=) | `94.64% <100.00%> (+7.40%)` | :arrow_up: |

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[neilalexander]

cc @S7evinK @devonh