Achieve compatibility with Scale8

[b1ron]

What should be done?

We are basically compatible with Scale8 according to their integration test results. The 2 failures below also occur when run using diff-proxy mode. The two created_at values which are causing the failures appear in the tests and are not generated or stored so they seem to be irrelevant.

    -         "created_at": 1608175440000,
    +         "created_at": 1608171840000,
---
Test Suites: 2 failed, 37 passed, 39 total
Tests:       2 failed, 90 passed, 92 total
Snapshots:   2 failed, 31 passed, 33 total
Time:        45.957 s
Ran all test suites.

From grepping through this file I found the below:

### Tasks
- [ ] https://github.com/FerretDB/FerretDB/issues/2013
- [ ] https://github.com/FerretDB/FerretDB/issues/1428
- [ ] https://github.com/FerretDB/FerretDB/issues/1423
- [ ] https://github.com/FerretDB/FerretDB/issues/1439
- [ ] https://github.com/FerretDB/FerretDB/issues/1413
- [ ] https://github.com/FerretDB/FerretDB/issues/1432
- [ ] https://github.com/FerretDB/FerretDB/issues/2888
- [ ] https://github.com/FerretDB/FerretDB/issues/2889
- [ ] https://github.com/FerretDB/FerretDB/issues/2890
- [ ] https://github.com/FerretDB/FerretDB/issues/2891
- [ ] https://github.com/FerretDB/FerretDB/issues/2892
- [ ] https://github.com/FerretDB/FerretDB/issues/2893
- [ ] https://github.com/FerretDB/FerretDB/issues/2897
- [ ] https://github.com/FerretDB/FerretDB/issues/2899
- [ ] https://github.com/FerretDB/FerretDB/issues/2900
- [ ] https://github.com/FerretDB/FerretDB/issues/2901
- [ ] https://github.com/FerretDB/FerretDB/issues/2902
- [ ] https://github.com/FerretDB/FerretDB/issues/2903
- [ ] https://github.com/FerretDB/FerretDB/issues/2128

[AlekSi]

@b1ron Please run https://github.com/awslabs/amazon-documentdb-tools/tree/master/compat-tool on it

[b1ron]

Done @AlekSi.