fix: fix slice init length

[cuishuang]

The intention here should be to initialize a slice with a capacity of len(shardFuncRegistry) rather than initializing the length of this slice.

The online demo: https://go.dev/play/p/q1BcVCmvidW

[Slach]

thanks for contribution

[coveralls]

Pull Request Test Coverage Report for Build 11179941054

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 263 unchanged lines in 10 files lost coverage.
• Overall coverage decreased (-1.9%) to 65.819%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/backup/restore.go	1	67.13%
cmd/clickhouse-backup/main.go	2	79.53%
pkg/storage/object_disk/object_disk.go	5	69.14%
pkg/config/config.go	8	73.23%
pkg/status/status.go	9	70.2%
pkg/backup/backuper.go	17	69.5%
pkg/server/server.go	18	56.8%
pkg/storage/general.go	20	60.54%
pkg/storage/s3.go	25	45.24%
pkg/storage/gcs.go	158	0.0%

Totals
Change from base Build 11109934324:	-1.9%
Covered Lines:	8825
Relevant Lines:	13408

---

💛 - Coveralls