Fix upmerge workflow to ignore `bicepconfig` #3115

Job	Run time
Sample tests (demo, ubuntu-latest, true, demo, default, ./samples/demo/app.bicep, --application d...	4m 19s
Sample tests (dapr, ubuntu-latest-m, true, dapr, default, ./samples/dapr/dapr.bicep, -p frontendI...	2m 43s
Sample tests (volumes, ubuntu-latest, true, myapp, default, ./samples/volumes/app.bicep, -p image...	1m 53s
Sample tests (eshop-containers, ubuntu-latest-m, true, eshop, default, ./samples/eshop/eshop.bice...	5m 39s
Sample tests (eshop-azure, ubuntu-latest-m, false, eshop, azure, ./samples/eshop/eshop.bicep, tes...	3s
Sample tests (eshop-aws, ubuntu-latest-m, false, eshop, aws, ./samples/eshop/eshop.bicep, tests/e...	2s
	14m 39s

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