Need to provide a registerer

[leizor]

This fixes the following panic when running:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0xa737a4]

goroutine 1 [running]:
github.com/grafana/influx2cortex/pkg/remotewrite.NewRecorder({0xbf0967, 0xc}, {0x0, 0x0})
	/go/src/github.com/grafana/influx2cortex/pkg/remotewrite/recorder.go:31 +0x2c4
github.com/grafana/influx2cortex/pkg/influx.NewProxy({{{0xbebbfa, 0x7}, 0x1f90, 0x0, 0x12a05f200, 0x6fc23ac00, 0x6fc23ac00, 0x6fc23ac00, 0xa00000, 0x2387, ...}, ...})
	/go/src/github.com/grafana/influx2cortex/pkg/influx/api.go:123 +0x47
main.main()
	/go/src/github.com/grafana/influx2cortex/cmd/influx2cortex/main.go:24 +0x298

[grafanabot]

Go coverage report:

Click to expand.

File	%
github.com/grafana/influx2cortex/pkg/errorx/errors.go	67.3%
github.com/grafana/influx2cortex/pkg/errorx/http_translator.go	100.0%
github.com/grafana/influx2cortex/pkg/influx/api.go	82.2%
github.com/grafana/influx2cortex/pkg/influx/errors.go	100.0%
github.com/grafana/influx2cortex/pkg/influx/parser.go	84.1%
github.com/grafana/influx2cortex/pkg/influx/recorder.go	91.7%
github.com/grafana/influx2cortex/pkg/remotewrite/client.go	69.1%
github.com/grafana/influx2cortex/pkg/remotewrite/measured_client.go	88.9%
github.com/grafana/influx2cortex/pkg/remotewrite/recorder.go	100.0%
github.com/grafana/influx2cortex/pkg/route/registerer.go	100.0%
github.com/grafana/influx2cortex/pkg/server/middleware/http_auth.go	0.0%
github.com/grafana/influx2cortex/pkg/server/middleware/http_fake_auth.go	0.0%
github.com/grafana/influx2cortex/pkg/server/middleware/instrument.go	6.7%
github.com/grafana/influx2cortex/pkg/server/middleware/logging.go	69.7%
github.com/grafana/influx2cortex/pkg/server/middleware/middleware.go	0.0%
github.com/grafana/influx2cortex/pkg/server/middleware/request_limits.go	81.8%
github.com/grafana/influx2cortex/pkg/server/middleware/response.go	57.1%
github.com/grafana/influx2cortex/pkg/server/middleware/route_matcher.go	0.0%
github.com/grafana/influx2cortex/pkg/server/middleware/tracer.go	13.0%
github.com/grafana/influx2cortex/pkg/server/server.go	83.3%
github.com/grafana/influx2cortex/pkg/tenant/resolver.go	75.6%
github.com/grafana/influx2cortex/pkg/tenant/tenant.go	91.7%
github.com/grafana/influx2cortex/pkg/util/bytereplacer/byte_replacer.go	100.0%
github.com/grafana/influx2cortex/pkg/util/extract_forwarded.go	66.7%
github.com/grafana/influx2cortex/pkg/util/http.go	68.3%
github.com/grafana/influx2cortex/pkg/util/log/experimental.go	0.0%
github.com/grafana/influx2cortex/pkg/util/log/log.go	0.0%
github.com/grafana/influx2cortex/pkg/util/log/rate_limit.go	90.0%
github.com/grafana/influx2cortex/pkg/util/log/wrappers.go	0.0%
github.com/grafana/influx2cortex/pkg/util/push/push.go	60.0%
total	65.4%

Go lint report:

No issues found. 😎

[ywwg]

oop yes sorry this became necessary after a refactor.

[ywwg]

make sure to select "squash and merge" from the green button dropdown menu (it will remember that choice for the future)