Fix CoroutineCollection.createIndexes

[skkap]

With the current implementation calling CoroutineCollection.createIndexes throws:

Caused by: java.lang.IllegalArgumentException: More than one onNext value for awaitSingle
	(Coroutine boundary)
	at org.litote.kmongo.coroutine.CoroutineCollection.createIndexes(CoroutineCollection.kt:823)
	at com.skkap.lookback.server.job.EnsureMongodbIndexesJob$ensureIndexes$2.invokeSuspend(EnsureMongodbIndexesJob.kt:18)
Caused by: java.lang.IllegalArgumentException: More than one onNext value for awaitSingle
	at kotlinx.coroutines.reactive.AwaitKt$awaitOne$2$1.onNext(Await.kt:240)
	at reactor.core.publisher.StrictSubscriber.onNext(StrictSubscriber.java:89)
	at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:201)
	at reactor.core.publisher.FluxIterable$IterableSubscription.fastPath(FluxIterable.java:340)
	at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:227)
...

I am not confident about the fix, but I believe createIndexes() returns more than one element from a publisher.

Please let me know if you have some suggestions.

[codecov]

Codecov Report

Merging #329 (d9bc2ae) into master (d0133a9) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master     #329      +/-   ##
============================================
- Coverage     57.17%   57.15%   -0.02%     
  Complexity      742      742              
============================================
  Files           131      131              
  Lines          5445     5445              
  Branches        508      508              
============================================
- Hits           3113     3112       -1     
- Misses         2103     2104       +1     
  Partials        229      229              

Impacted Files	Coverage Δ
...org/litote/kmongo/coroutine/CoroutineCollection.kt	49.39% <0.00%> (ø)
...litote/kmongo/coroutine/CoroutineClientSessions.kt	75.00% <0.00%> (-25.00%)	⬇️

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[zigzago]

Thank you for the PR