jobs/templates/debian: Fix cassandra chunk keys

[1] Shows the concatenated chunks are wrong, this fixes it

[1] https://jenkins.softwareheritage.org/view/Debian%20packages/job/debian/job/packages/job/DSTO/job/gbp-buildpackage/168/execution/node/3/ws/keys/cassandra.asc/*view*/

jobs/templates/debian/keys/cassandra.1.asc

@@ -998,3 +998,4 @@ iuOIRgQQEQIABgUCQxCsXAAKCRCEibFNiAdSm/TcAJ4lUvE2VGlmy5TbSZZni8nJ
 3EfKFur2AJ90GbAp1X1kF1RTyCBglXLLSiQLhgCfQMoBmSTIC26Cw5rtis1bD3ti
 AYCIRgQTEQIABgUCQxDK6wAKCRDuJd4/HNsP43qJAJ4qC9c8aTiP490BzZBmj7ih
 RsM+WwCeJpxyMNAX0QLpWQj4zNOqsubOqmGIRgQQEQIABgUCQxsrNQAKCRBp0qYd
+

jobs/templates/debian/keys/cassandra.2.asc

@@ -688,3 +688,4 @@ vHIFWoNGj6PDAQdOP4hGBBgRAgAGBQJACc6dAAoJEPg1j6LygzyTbBQAoLlfupns
 w3+Cv7oqCqvT5skUjslhAJ4zKFzVctl/drQ6dSYCvDjXYJGxtQ==
 =XwUQ
 -----END PGP PUBLIC KEY BLOCK-----
+

jobs/templates/debian/keys/cassandra.3.asc

@@ -698,3 +698,4 @@ RcmKenDIfuknrqFOgsF232O+20TwUidocIikZ9jZfv/UBTTjGiUdw1HMoIb5/nFn
 MZhBjcXknw==
 =607X
 -----END PGP PUBLIC KEY BLOCK-----
+

jobs/templates/debian/keys/cassandra.4.asc

@@ -533,3 +533,4 @@ aF4Pcs75aALTXIamt62MKRbd4Uxh6gRiAOZF3muNYt7xnDvNtIoQl7WHVq8Y+db3
 lSILgQ==
 =Hk6U
 -----END PGP PUBLIC KEY BLOCK-----
+