fix: fix slice init length

[wangjingcun]

Changes

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

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

Fixes

fix slice init length

Tests

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• blobber:
• 0chain:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...