Fixing YAML block scalar when providing sshKey for git-sync

[RobinM-code]

YAML block scalar |- will strip any final empty newline after the last line. This results in a ssh-key that can not be read by libcrypto. YAML block scalar | will preserve any final empty newline after the last line. This makes sure the ssh-key can be read.

closes: #56706 (comment)

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