replicate ls: fix panic

[poornas]

due to older style ARN

Description

$ ./mc replicate ls alias/bucket
Rules:
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x30 pc=0xf6755b]

goroutine 1 [running]:
github.com/minio/mc/cmd.replicateListMessage.String({{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, {{{0x0, 0x0}, {0xc0001d02b0, 0x4}}, ...}, ...})
        github.com/minio/mc/cmd/replicate-ls.go:105 +0x23b
github.com/minio/mc/cmd.printMsg({0x147cc88?, 0xc0005401e0?})
        github.com/minio/mc/cmd/print.go:38 +0x11c
github.com/minio/mc/cmd.mainReplicateList(0xc000683380)
        github.com/minio/mc/cmd/replicate-ls.go:157 +0x689
github.com/minio/cli.HandleAction({0x10a38a0?, 0x130ca38?}, 0x2?)
        github.com/minio/cli@v1.24.2/app.go:490 +0x5a
github.com/minio/cli.Command.Run({{0x125914e, 0x2}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x12a26b9, 0x30}, {0x0, ...}, ...}, ...)
        github.com/minio/cli@v1.24.2/command.go:242 +0x9b7
github.com/minio/cli.(*App).RunAsSubcommand(0xc00097a000, 0xc000503380)
        github.com/minio/cli@v1.24.2/app.go:380 +0x7bb
github.com/minio/cli.Command.startApp({{0x1262ffb, 0x9}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1296b82, 0x28}, {0x0, ...}, ...}, ...)
        github.com/minio/cli@v1.24.2/command.go:346 +0x6c9
github.com/minio/cli.Command.Run({{0x1262ffb, 0x9}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1296b82, 0x28}, {0x0, ...}, ...}, ...)
        github.com/minio/cli@v1.24.2/command.go:117 +0x438
github.com/minio/cli.(*App).Run(0xc0005321c0, {0xc00003e080, 0x4, 0x4})
        github.com/minio/cli@v1.24.2/app.go:260 +0x827
github.com/minio/mc/cmd.Main({0xc00003e080?, 0x4, 0x4})
        github.com/minio/mc/cmd/main.go:141 +0x3e

Motivation and Context

How to test this PR?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Unit tests added/updated
• Internal documentation updated
• Create a documentation update request here

[vadmeste]

LGTM