test: Add mutex and setter/getter for addresses in test

[paul1r]

What this PR does / why we need it:
Before fix:

==================
WARNING: DATA RACE
Read at 0x00c0001e6c10 by goroutine 433:
  sort.StringSlice.Less()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/sort/sort.go:154 +0x6c
  sort.(*StringSlice).Less()
      <autogenerated>:1 +0x20
  sort.insertionSort()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/sort/zsortinterface.go:12 +0xd8
  sort.pdqsort()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/sort/zsortinterface.go:73 +0x2c8
  sort.Sort()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/sort/sort.go:51 +0x6c
  sort.Strings()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/sort/sort.go:176 +0x154
  github.com/grafana/loki/v3/pkg/bloomgateway.(*JumpHashClientPool).updateLoop()
      /Users/progers/dev/src/github.com/grafana/loki/pkg/bloomgateway/client_pool.go:107 +0x140
  github.com/grafana/loki/v3/pkg/bloomgateway.NewJumpHashClientPool.func1()
      /Users/progers/dev/src/github.com/grafana/loki/pkg/bloomgateway/client_pool.go:62 +0x58

Previous write at 0x00c0001e6c10 by goroutine 430:
  github.com/grafana/loki/v3/pkg/bloomgateway.TestJumpHashClientPool_UpdateLoop()
      /Users/progers/dev/src/github.com/grafana/loki/pkg/bloomgateway/client_pool_test.go:28 +0x1f4
  testing.tRunner()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1595 +0x1b0
  testing.(*T).Run.func1()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1648 +0x40

Goroutine 433 (running) created at:
  github.com/grafana/loki/v3/pkg/bloomgateway.NewJumpHashClientPool()
      /Users/progers/dev/src/github.com/grafana/loki/pkg/bloomgateway/client_pool.go:62 +0x4e4
  github.com/grafana/loki/v3/pkg/bloomgateway.TestJumpHashClientPool_UpdateLoop()
      /Users/progers/dev/src/github.com/grafana/loki/pkg/bloomgateway/client_pool_test.go:23 +0xe4
  testing.tRunner()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1595 +0x1b0
  testing.(*T).Run.func1()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1648 +0x40

Goroutine 430 (running) created at:
  testing.(*T).Run()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1648 +0x5e8
  testing.runTests.func1()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:2054 +0x80
  testing.tRunner()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1595 +0x1b0
  testing.runTests()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:2052 +0x6e4
  testing.(*M).Run()
      /opt/homebrew/Cellar/go/1.21.6/libexec/src/testing/testing.go:1925 +0x9ec
  main.main()
      _testmain.go:89 +0x294
==================

After fix:

go test -race -count=100 . -run TestJumpHashClientPool_UpdateLoop   
ok  	github.com/grafana/loki/v3/pkg/bloomgateway	21.858s

Which issue(s) this PR fixes:
Relates to: #8586

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
• 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