fix(go-build-alpine): honour OONI_PSIPHON_TAGS (#968)

Closes https://github.com/ooni/probe/issues/2334.

While there, reinstate integration tests, which were also lost in a previous refactoring. However, only run those tests for linux/amd64 because we can be confident that the Go compiler is WAI for all archs we support.

While there, always use bash for running end-to-end tests.

H/T @ainghazal for discovering and reporting this bug.

CLI/go-build-alpine

@@ -8,9 +8,11 @@ export GOCACHE=$GOCACHE
 export GOMODCACHE=$GOMODCACHE
 export GOOS=$GOOS
 export GOARCH=$GOARCH
+export OONI_PSIPHON_TAGS=${OONI_PSIPHON_TAGS:-}
 for PACKAGE in $@; do
 	PRODUCT=$(basename $PACKAGE)
 	go build -o ./CLI/$PRODUCT-$GOOS-$OONIARCH \
+		-tags=$OONI_PSIPHON_TAGS \
 		-ldflags='-s -w -extldflags "-static"' \
 		$GOLANG_EXTRA_FLAGS $PACKAGE
 done