it: enable 4 out of 5 TimestampTests

The remaining test (MonotonicTimestampGenerator) needs further adjustments.
Currently it segfaults - I'll create a separate issue for this one.

TLDR - currently, the generator provided to `cass_cluster_set_timestamp_gen`
is constructed using pure c++ API (no API from cassandra.h is used).
It depends on `src/timestamp_generator.cpp`, which we should ultimately remove.
However, to remove this file, we need to implement a testing utility which
allows us to read the generated timestamps during the test. The test would
then need to be rewritten using this new utility.

Author: muzarski

Makefile

@@ -25,6 +25,7 @@ SCYLLA_TEST_FILTER := $(subst ${SPACE},${EMPTY},ClusterTests.*\
 :LoggingTests.*\
 :PreparedMetadataTests.*\
 :UseKeyspaceCaseSensitiveTests.*\
+:TimestampTests.*\
 :MetricsTests.Integration_Cassandra_ErrorsRequestTimeouts\
 :MetricsTests.Integration_Cassandra_Requests\
 :MetricsTests.Integration_Cassandra_StatsShardConnections\
@@ -37,6 +38,7 @@ SCYLLA_TEST_FILTER := $(subst ${SPACE},${EMPTY},ClusterTests.*\
 :ExecutionProfileTest.Integration_Cassandra_LatencyAwareRouting\
 :-PreparedTests.Integration_Cassandra_PreparedIDUnchangedDuringReprepare\
 :HeartbeatTests.Integration_Cassandra_HeartbeatFailed\
+:TimestampTests.Integration_Cassandra_MonotonicTimestampGenerator\
 :ControlConnectionTests.Integration_Cassandra_TopologyChange\
 :ControlConnectionTests.Integration_Cassandra_FullOutage\
 :ControlConnectionTests.Integration_Cassandra_TerminatedUsingMultipleIoThreadsWithError\
@@ -73,6 +75,7 @@ CASSANDRA_TEST_FILTER := $(subst ${SPACE},${EMPTY},ClusterTests.*\
 :LoggingTests.*\
 :PreparedMetadataTests.*\
 :UseKeyspaceCaseSensitiveTests.*\
+:TimestampTests.*\
 :MetricsTests.Integration_Cassandra_ErrorsRequestTimeouts\
 :MetricsTests.Integration_Cassandra_Requests\
 :MetricsTests.Integration_Cassandra_StatsShardConnections\
@@ -86,6 +89,7 @@ CASSANDRA_TEST_FILTER := $(subst ${SPACE},${EMPTY},ClusterTests.*\
 :-PreparedTests.Integration_Cassandra_PreparedIDUnchangedDuringReprepare\
 :PreparedTests.Integration_Cassandra_FailFastWhenPreparedIDChangesDuringReprepare\
 :HeartbeatTests.Integration_Cassandra_HeartbeatFailed\
+:TimestampTests.Integration_Cassandra_MonotonicTimestampGenerator\
 :ControlConnectionTests.Integration_Cassandra_TopologyChange\
 :ControlConnectionTests.Integration_Cassandra_FullOutage\
 :ControlConnectionTests.Integration_Cassandra_TerminatedUsingMultipleIoThreadsWithError\