test: add integration test for accepting an invite to an empty room

[paul8711-code]

This PR is related to #4642. I have added the second of the two requested integration tests, according to which accepting an invite did indeed not work, but instead threw a completely different error than mentioned.

• I've documented the public API changes in the appropriate changelog files (see Writing changelog entries).
• This PR was made with the help of AI.

Signed-off-by: Paul8711 154304377+paul8711-code@users.noreply.github.com

[paul8711-code]

@Hywan could you also take a look at this PR? It too is relevant to our discussion in the mentioned issue.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
2066	1	2065	0

View the top 1 failed test(s) by shortest run time

matrix-sdk-integration-testing::tests::room::test_empty_room_accept_invite

Stack Traces | 0.806s run time

Error: the server returned an error: [404 / M_UNKNOWN] Can't join remote room because no servers that are in the room have been provided.

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[codspeed-hq]

Merging this PR will degrade performance by 40.36%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 49 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	Restore session [memory store]	167.6 ms	281 ms	-40.36%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing paul8711-code:fix/empty-room-invite-accept-forbidden (b56fa22) with main (567463d)}

[Hywan]

Thanks for the test! I think we need to improve it a bit though.