Update sync method to leave out unneeded bytes

[ShadowJonathan]

(And fix some tests to stop assuming unilateral presence of sync keys)

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(Partially) addresses #6579 (room.join is not optimized)

Note: This PR is potentially breaking, it still adheres to the spec, but some clients or libraries could have (up to this point) fully assumed that all keys are present in the /sync object.

Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>

[ShadowJonathan]

Looks like the tests are blocked because sytest assumes some keys in /sync will be present...

[clokep]

@ShadowJonathan Curious if you plan to keep working on this? A PR could be made to modify sytest to avoid the unnecessary keys.

[ShadowJonathan]

@clokep this is still blocked because of test logic in sytest, which asserts that these keys are needed.

Does synapse still test with sytest?

[clokep]

@clokep this is still blocked because of test logic in sytest, which asserts that these keys are needed.

Right -- but we can change sytest. sytest isn't immutable.

Does synapse still test with sytest?

Yes.

[ShadowJonathan]

Well, then i cant progress on this.

And by the way, if that's so, then sytest is not compatible with the spec, then its incorrect to assert those keys should be there.

The spec says those keys are optional, sytest asserts otherwise, sytest is wrong, and thus should be changed, and thats why its blocked on that.

Further discussion in here, please; matrix-org/sytest#957

And no, this PR is just blocked, if you wanna unblock it, resolve that issue first, please, dont just close it because its taking space.

[ShadowJonathan]

(Converting to draft due to unknown status of the dependant issue at this time)

[ShadowJonathan]

Due to no progress with this PR for a while, and because of some outstanding other projects i'd need to focus on, im closing this PR for the time being. I'll probably re-open it if or when i get back on track with misc issues like these.