Bump github.com/aws/aws-sdk-go from 1.44.15 to 1.48.4 in /extension/observer/ecsobserver #8678

Job	Run time
setup-environment	8m 17s
loadtest (TestIdleMode)	1m 55s
loadtest (TestBallastMemory\|TestLog10kDPS)	5m 29s
loadtest (TestMetric10kDPS\|TestMetricsFromFile)	2m 41s
loadtest (TestMetricResourceProcessor\|TestTrace10kSPS)	3m 34s
loadtest (TestTraceNoBackend10kSPS\|TestTrace1kSPSWithAttrs)	3m 22s
loadtest (TestTraceBallast1kSPSWithAttrs\|TestTraceBallast1kSPSAddAttrs)	4m 6s
loadtest (TestTraceAttributesProcessor)	1m 54s
	31m 18s

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