ci: Re-enable and fix NSE test

[andybalaam]

Makes https://github.com/matrix-org/matrix-rust-sdk/issues/3411 less bad because it should fail fast.

It also seems to make it fail less often, so it might be worth re-enabling the test (which this PR does) and seeing whether it gives us clues.

Re-opening this PR as @bnjbvr suggested it might be worth re-enabling the test. I'm happy to leave it disabled, delete it, or re-enable it as people wish.

[andybalaam]

I've had to stop working on this.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.19%. Comparing base (b57dbd8) to head (c7d07cd). Report is 22 commits behind head on main.

:exclamation: Current head c7d07cd differs from pull request most recent head 6a2419f

Please upload reports for the commit 6a2419f to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3417      +/-   ##
==========================================
+ Coverage   82.97%   83.19%   +0.22%     
==========================================
  Files         246      246              
  Lines       24958    24958              
==========================================
+ Hits        20708    20765      +57     
+ Misses       4250     4193      -57     

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[bnjbvr]

Hah, managed to make it permafail in the CodeCov task just by rejiggering the logic.

I propose to shelve the PR, but keep it open; as soon as anyone has a bit of free time, they should feel free to investigate it, because it does seem to exhibit some real issues.

[bnjbvr]

This didn't get any activity for a while, so closing.