[Storage] Manage fetcherService from a data race safe singleton #5546

Job	Run time
quickstart (swift, macos-14, Xcode_15.3)	3m 6s
quickstart-ftl-cron-only	0s
pod-lib-lint (ios, macos-14)	3m 25s
pod-lib-lint (ios, macos-13)	12m 19s
pod-lib-lint (tvos, macos-14)	3m 15s
storage-integration-tests (Swift)	18m 39s
pod-lib-lint (tvos, macos-13)	6m 20s
storage-integration-tests (ObjC)	9m 14s
spm (iOS, macos-13)	10m 43s
pod-lib-lint (macos, macos-14)	3m 2s
spm (iOS, macos-14)	6m 9s
pod-lib-lint (macos, macos-13)	5m 3s
spm (tvOS, macos-13)	9m 10s
pod-lib-lint (watchos, macos-14)	2m 26s
spm (tvOS, macos-14)	5m 37s
pod-lib-lint (watchos, macos-13)	6m 5s
spm (macOS, macos-13)	6m 58s
spm (macOS, macos-14)	4m 57s
spm (catalyst, macos-13)	5m 55s
spm (catalyst, macos-14)	5m 34s
spm (watchOS, macos-13)	9m 5s
spm (watchOS, macos-14)	6m 23s
spm (macos-14, visionOS, Xcode_15.3)	6m 3s
storage-cron-only	0s
	2h 29m 28s

Provide feedback