[*] refactor object changes metric

[pashagolub]

Rewrite the function so it follows the common calling conventions. Make sure Reaper.FetchMetric() exits if none measurements collected

[coveralls]

Pull Request Test Coverage Report for Build 18282923545

Details

• 5 of 21 (23.81%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.4%) to 70.862%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/reaper/metric.go	0	1	0.0%
internal/reaper/reaper.go	0	2	0.0%
internal/reaper/database.go	5	18	27.78%

Files with Coverage Reduction	New Missed Lines	%
internal/reaper/database.go	1	76.38%

Totals
Change from base Build 18228262317:	0.4%
Covered Lines:	3536
Relevant Lines:	4990

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💛 - Coveralls