Fix sliding sync for rooms with unknown room version #3294

Job	Run time
check-lockfile	8s
check-lockfile	8s
lint-newsfile	34s
lint-newsfile	34s
changes	2s
changes	2s
lint-crlf	6s
lint-crlf	6s
check-schema-delta	39s
check-schema-delta	39s
Typechecking	1m 15s
Typechecking	1m 15s
check-sampleconfig	55s
check-sampleconfig	55s
lint	27s
lint	27s
lint-pydantic	55s
lint-pydantic	55s
lint-clippy-nightly	0s
lint-clippy-nightly	0s
lint-clippy	0s
lint-clippy	0s
lint-readme	0s
lint-readme	0s
lint-rustfmt	0s
lint-rustfmt	0s
linting-done	2s
linting-done	2s
calculate-test-jobs	4s
calculate-test-jobs	4s
portdb (3.8, 11)	3m 16s
portdb (3.8, 11)	3m 16s
cargo-test	0s
cargo-test	0s
complement (monolith, SQLite)	12m 41s
complement (monolith, SQLite)	12m 41s
portdb (3.11, 15)	3m 8s
portdb (3.11, 15)	3m 8s
trial-olddeps	8m 2s
trial-olddeps	8m 2s
complement (monolith, Postgres)	13m 10s
complement (monolith, Postgres)	13m 10s
complement (workers, Postgres)	19m 58s
complement (workers, Postgres)	19m 58s
trial-pypy	0s
trial-pypy	0s
cargo-bench	0s
cargo-bench	0s
trial (3.8, sqlite, all)	5m 39s
trial (3.8, sqlite, all)	5m 39s
sytest (focal)	8m 15s
sytest (focal)	8m 15s
trial (3.8, postgres, 11, all)	13m 29s
trial (3.8, postgres, 11, all)	13m 29s
sytest (focal, postgres)	10m 24s
sytest (focal, postgres)	10m 24s
trial (3.8, sqlite)	5m 12s
trial (3.8, sqlite)	5m 12s
sytest (focal, multi-postgres, workers)	28m 52s
sytest (focal, multi-postgres, workers)	13m 25s
sytest (focal, multi-postgres, workers, asyncio)	18m 45s
sytest (focal, multi-postgres, workers, asyncio)	18m 45s
export-data	2m 25s
export-data	2m 25s
tests-done	3s
tests-done	2s
	5h 1m 24s

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