Host/username secret values contain trailing newlines, sanitization fix breaks SSH key

Commit 83fe6f288 added tr -d '\n\r' to sanitize host and username values before base64 encoding in the host-access secret. This fixed trailing newlines in host/username but also stripped newlines from id_rsa, breaking the PEM format.

Commit 0e675cb76 reverted the fix entirely, which brought back the trailing newline problem — SSH fails with Could not resolve hostname because the host value includes \n.

Neither state works:

• main (reverted): valid SSH key, broken hostname
• 83fe6f288: clean hostname, broken SSH key

The fix is to sanitize host and username but not id_rsa:

host: $(cat /opt/host-info/host | tr -d '\n\r' | base64 -w0)
username: $(cat /opt/host-info/username | tr -d '\n\r' | base64 -w0)
id_rsa: $(cat /opt/host-info/id_rsa | base64 -w0)

Affects all tkn/infra-aws-*.yaml tasks.

Inspect the host-access secret commands in all tkn/infra-aws-*.yaml tasks and compare the handling of host, username, and id_rsa. Verify that host and username values no longer contain trailing newlines while the SSH key retains its PEM newlines, then validate that the SSH task resolves the hostname and accepts the key.