DATAJPA-1544 - Delete totals.size() == 1 condition in count method

[JIANGc]

The totals.get(0) cannot always get the correct count result no matter
whether there is a group by clause or not. There is also
misunderstanding when we use getTotalElements method for paging.

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[schauder]

This change causes a couple of test failures in UserRepositoryFinderTests UserRepositoryTests and tests derived from that.

@JIANGc can you take a look if this can be saved?

[JIANGc]

Thanks @schauder . I made some updates and fixed unit tests.

[schauder]

To be honest I don't really grasp what is going on here.

I guess it starts with the previously existing version of the source code, which is bogus AFAIK since a count query must always return exactly one value.
Therefore this PR should be done on top of #400.

Any parsing of queries should happen where all the other parsing happens inside AstractJpaQuery derivatives.

And finally and possibly most crucial: The problem is that the generation of the count query is broken so that is the location that should get fixed.

[gregturn]

As stated, this needs to be redone, on top of #400. I think starting from there with a fresh PR, will do much better.