RNET-1126: Fix flaky tests on CI

[papafe]

Fixes #3560

[coveralls-official]

Pull Request Test Coverage Report for Build 9594797197

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 112 unchanged lines in 17 files lost coverage.
• Overall coverage decreased (-1.3%) to 78.817%

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Files with Coverage Reduction	New Missed Lines	%
Realm/Realm/Dynamic/MetaRealmObject.cs	1	56.55%
Realm/Realm/Dynamic/DynamicAsymmetricObject.cs	1	0.0%
Realm/Realm/DatabaseTypes/RealmCollectionBase.cs	1	83.98%
Realm/Realm/Handles/ObjectHandle.cs	1	90.61%
Realm/Realm/Configurations/RealmConfigurationBase.cs	1	95.35%
Realm/Realm/Dynamic/DynamicRealmObjectHelper.cs	2	68.42%
Realm/Realm/Configurations/FlexibleSyncConfiguration.cs	2	92.54%
Realm/Realm/Exceptions/Sync/SubscriptionException.cs	2	0.0%
Realm/Realm/Helpers/SerializationHelper.cs	3	52.42%
Realm/Realm/Handles/SessionHandle.cs	5	81.97%

Totals
Change from base Build 8937828998:	-1.3%
Covered Lines:	6617
Relevant Lines:	8241

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💛 - Coveralls

[papafe]

The cause of the flakyness seems to be due to some various timing issues:

• Reusing the same object for different tests led to realm exceptions when adding an object with the same primary key
• When objects are added directly to Atlas, the synchronization of objects does not respect the boundaries of changesets, that can be broken down in smaller pieces (especially when working with links). This means that sometimes the elements of collections of links are not added all together, and this did not work with our expectations. This is the reason I've added much more WaitForConditions.