Running OSMetricsCollector before metric collection begins

[khushbr]

Running OSMetricsCollector before metric collection begins to allow jTidMap to be persisted.

Fixes #: #586

Description of changes: OSMetricsCollector#collectMetrics() is responsible for persisting Thread related info in 'jTidMap'
In case the 'jTidMap' has not been updated and threadState is null, we return -1 when getNativeThreadId() is invoked. This happens during the first round of collectors execution, any collector executed before OSMetricsCollector will find the threadState as null in the 'jTidMap' and persist -1 value for threadID.

Tests:

If new tests are added, how long do the new ones take to complete

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