fix ScyllaDB: lost page results due to not fetched the entire page

[javeme]

fix #1340

Change-Id: Ib89d9790af4236a137d9215e27f0d17f0de10afd

[javeme]

why set remaining = getAvailableWithoutFetching(): https://support.datastax.com/hc/en-us/articles/115003076346-FAQ-Why-does-Java-driver-setFetchSize-return-all-rows-

[javeme]

ci error of cassandra backend:

[ERROR] Tests run: 684, Failures: 1, Errors: 0, Skipped: 21, Time elapsed: 513.523 s <<< FAILURE! - in com.baidu.hugegraph.core.CoreTestSuite
[ERROR] testAddEdgeWithTtlAndTtlStartTime(com.baidu.hugegraph.core.EdgeCoreTest)  Time elapsed: 1.872 s  <<< FAILURE!
java.lang.AssertionError
	at com.baidu.hugegraph.core.EdgeCoreTest.testAddEdgeWithTtlAndTtlStartTime(EdgeCoreTest.java:754)

It's ok after retry. seems the reason is: current testAddEdgeWithTtlAndTtlStartTime use the timestamp of the previous test case used.

[codecov]

Codecov Report

Merging #1407 (92c91dc) into master (f57ad0d) will increase coverage by 0.33%.
The diff coverage is 65.33%.

@@             Coverage Diff              @@
##             master    #1407      +/-   ##
============================================
+ Coverage     61.89%   62.22%   +0.33%     
- Complexity     5811     5857      +46     
============================================
  Files           386      381       -5     
  Lines         32192    32135      -57     
  Branches       4497     4504       +7     
============================================
+ Hits          19924    19995      +71     
+ Misses        10230    10089     -141     
- Partials       2038     2051      +13     

Impacted Files	Coverage Δ	Complexity Δ
.../hugegraph/backend/store/rocksdb/RocksDBTable.java	71.53% <0.00%> (ø)	37.00 <0.00> (ø)
...egraph/backend/store/cassandra/CassandraTable.java	79.16% <60.00%> (+3.28%)	87.00 <8.00> (+7.00)
...ackend/store/cassandra/CassandraEntryIterator.java	72.46% <63.15%> (-14.21%)	21.00 <3.00> (+1.00)	⬇️
...egraph/backend/serializer/BinaryEntryIterator.java	85.18% <71.42%> (-0.53%)	21.00 <4.00> (-1.00)
.../hugegraph/backend/store/BackendEntryIterator.java	64.78% <72.22%> (+0.85%)	20.00 <4.00> (+2.00)
...va/com/baidu/hugegraph/backend/page/PageState.java	97.22% <100.00%> (+0.07%)	14.00 <1.00> (ø)
...ava/com/baidu/hugegraph/api/profile/GraphsAPI.java	20.75% <0.00%> (-3.69%)	0.00% <0.00%> (ø%)
...ph/backend/store/AbstractBackendStoreProvider.java	87.91% <0.00%> (-3.66%)	25.00% <0.00%> (+1.00%)	⬇️
...gegraph/backend/store/rocksdb/RocksDBFeatures.java	78.26% <0.00%> (-3.56%)	18.00% <0.00%> (ø%)
...in/java/com/baidu/hugegraph/StandardHugeGraph.java	68.83% <0.00%> (-1.56%)	119.00% <0.00%> (ø%)
... and 53 more

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[javeme]

TODO: ensure return the full page to users which scylla fetched to local.

[zhoney]

E.checkNotNull(page, "page");