[chore][workflow] only run for main repository (#37086) #48566

Job	Run time
setup-environment	4m 8s
loadtest (TestIdleMode)	4m 21s
loadtest (TestLog10kDPS\|TestLogOtlpSendingQueue)	8m 4s
loadtest (TestLogLargeFiles\|TestLargeFileOnce)	10m 34s
loadtest (TestMemoryLimiterHit\|TestMetric10kDPS)	6m 2s
loadtest (TestMetricsFromFile\|TestMetricResourceProcessor)	4m 19s
loadtest (TestSyslogComplementaryRFC5424\|TestSyslogComplementaryRFC3164)	3m 36s
loadtest (TestTrace10kSPS\|TestTrace10kSPSJaegerGRPC)	6m 51s
loadtest (TestTraceNoBackend10kSPS\|TestTrace1kSPSWithAttrs)	5m 38s
loadtest (TestTraceAttributesProcessor\|TestTraceAttributesProcessorJaegerGRPC)	4m 12s
update-benchmarks	0s
	57m 45s

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