dynamodb code not incrementing a counter

[johnabass]

A recent change has caused a bug where the dynamodb code doesn't seem to be incrementing the testDynamoCounter metric.

The relevant test output is:

=== RUN   TestMeasuresUpdate/Consumed_Capacity_Missing
    assert.go:81: 
            Error Trace:    /home/runner/go/pkg/mod/github.com/xmidt-org/touchstone@v0.1.6/touchtest/assert.go:81
                                        /home/runner/work/argus/argus/store/dynamodb/instrumenting_test.go:252
            Error:          Received unexpected error:
                            expected metric name(s) not found: [testDynamoCounter]
            Test:           TestMeasuresUpdate/Consumed_Capacity_Missing
            Messages:       Failed to match expected metrics: [testQueriesCounter testDynamoCounter]
    instrumenting_test.go:252: 
            Error Trace:    /home/runner/work/argus/argus/store/dynamodb/instrumenting_test.go:252
            Error:          Should be true
            Test:           TestMeasuresUpdate/Consumed_Capacity_Missing

[denopink]

on it