fix(blooms): Fix panic in initialisation of the bloom planner and builder

[chaudum]

What this PR does / why we need it:

The targets bloom-planner and bloom-builder panic at startup on branch main.

$ make loki && ./cmd/loki/loki -target=bloom-builder
CGO_ENABLED=0 go build -ldflags "-extldflags \"-static\" -s -w -X github.com/grafana/loki/v3/pkg/util/build.Branch=main -X github.com/grafana/loki/v3/pkg/util/build.Version=main-b29b4b4 -X github.com/grafana/loki/v3/pkg/util/build.Revision=b29b4b4bb -X github.com/grafana/loki/v3/pkg/util/build.BuildUser=christian@grafana1210 -X github.com/grafana/loki/v3/pkg/util/build.BuildDate=2024-09-11T08:30:11Z" -tags netgo -o cmd/loki/loki ./cmd/loki
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x287b590]

goroutine 1 [running]:
github.com/grafana/dskit/ring.(*BasicLifecycler).GetInstanceID(...)
	/home/christian/sandbox/grafana/loki/vendor/github.com/grafana/dskit/ring/basic_lifecycler.go:132
github.com/grafana/loki/v3/pkg/bloombuild/builder.New({{0x6400000, 0x6400000, {0x0, 0x0}, 0x0, 0x0, 0x0, {0x5f5e100, 0x2540be400, 0xa}, ...}, ...}, ...)
	/home/christian/sandbox/grafana/loki/pkg/bloombuild/builder/builder.go:92 +0x470
github.com/grafana/loki/v3/pkg/loki.(*Loki).initBloomBuilder(0xc002984008)
	/home/christian/sandbox/grafana/loki/pkg/loki/modules.go:1750 +0x4b6
github.com/grafana/dskit/modules.(*Manager).initModule(0xc000d2e6f0, {0x7ffe36edcb45, 0xd}, 0xc0027a22f8, 0xc0013ce960)
	/home/christian/sandbox/grafana/loki/vendor/github.com/grafana/dskit/modules/modules.go:136 +0x1ea
github.com/grafana/dskit/modules.(*Manager).InitModuleServices(0xc000d2e6f0, {0xc000dbeed0, 0x1, 0x7510c18f88e2e5ce?})
	/home/christian/sandbox/grafana/loki/vendor/github.com/grafana/dskit/modules/modules.go:108 +0xe8
github.com/grafana/loki/v3/pkg/loki.(*Loki).Run(0xc002984008, {0x0?, {0x4?, 0x2?, 0x6457fc0?}})
	/home/christian/sandbox/grafana/loki/pkg/loki/loki.go:497 +0x97
main.main()
	/home/christian/sandbox/grafana/loki/cmd/loki/main.go:129 +0x131e

This is because t.indexGatewayRingManager is not nil and therefore incorrectly tries to initialize the ring watcher, which fails.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[grafanabot]

This PR must be merged before a backport PR will be created.

[grafanabot]

This PR must be merged before a backport PR will be created.

[grafanabot]

This PR must be merged before a backport PR will be created.