Remove unused 'worker_cot_key'

This is, in fact, not CoT-related at all.  It's the old encrypted env
var key, and we removed support for that ages ago in taskcluster/taskcluster@b22b813

fake_secrets.yaml

@@ -1,47 +1,4 @@
 ---
-# generated with ssh-keygen -t rsa
-- name: worker_cot_key
-  path: /etc/taskcluster/secrets/worker_cot_key
-  value: |
-    -----BEGIN RSA PRIVATE KEY-----
-    MIIEowIBAAKCAQEAwjwEarILpzMKeyAGibgwV133FP8h/v72dElV0LWSOW/Ce3eM
-    ubIyfYq+w7pXnWL92Vnf4ieVTQFA0AHtx3WP2YVfwRh/XXvhgNPJtlAHsKfEu/7l
-    BQUsboF/dYvsS22UK5x0LG9Z0Mu+UQf3n0L/7EnfFF9hlZDvAQ97usavsjP68omz
-    a0TNcMK1H6qpwLS6g5vALGV8gYZROjqzemuMPgo2of0tMebYwBRgInco/Oan64Qt
-    CIymAanBqrHVXf+vEfKkwNa1PH9mG3a3smePJKqR8Fy3q1w8xtkwLWbkfFxX+NmM
-    pEWm2/BlbHPXnrU38ffmQJNzEUqKVS4Oy091uwIDAQABAoIBAQCxp8GGcXlVIcs5
-    WM6CEtUsZAbFzqIioMN9E0KJljm7jSw+T9eIVaP2zfuz/HF8w/lZXun26auWdkn4
-    t3rsD+xV0bcGX8jHEbLtaUk7FrIh8yFvrjF9SQEdxhZ1xliHmR+IUB62Mdbdsi1N
-    4lKr+dUpI1wGP0N7UMg6mRXbfTVgcLDYt+DvmWjTfKv9GVEv2za3YpwScaZzy4M7
-    lc7oe7y5uW3LJaR8l3thjbR/K3rnjzhzpmHCJ4qLBrBWvDOMAdx81EjGITUDm7e3
-    wrGiIfPBCqw97JUX+Rc+BKHVSQnDAt7P59BzPR04QQmN1Is9nNiMAu1NIgU/TqKL
-    Xmn0XGVJAoGBAOPm8uxikgM5QcOg8TAf7cyojfhZ7ptbIp5GNRBOQSBansdfBoUd
-    lQQB1lLRt6FTupZ07h/EIA9NYUzTn2jcDAGsOEiVkOi6HdNAfEQQaclZfXr3aST7
-    9hlHYvVC8qJ9ogqLMDILcwOuCYrh0o1gxAiWdg4yRd7if5hyqJbqig9FAoGBANou
-    cqLE66g0iI0+ufXzzFiiT8UTaROzW48VPmogkWRYI0zEzNkFV6TC6yCNIcyI3ROt
-    D1fI7A7rHSZTSJ4+W3zr9TH6DpG6VCqdD0LhAfITqmMlleYbauh8DNEGCg64c0XE
-    hE/4nwuMyaFDXTKBLhbPWCOWb21OE4j1GWRXJUD/AoGADX4W07fiPR6erh5RKTA6
-    u+sevJ1WawwyOHyfl5+Ka4fx7ovJrwfZUqtpLO4NmReD7HRvxKGv5DgIkqvUvDiK
-    3W58xo9UTPL34RHoSX9PRARwUV9kcjQYldaMHUkhZE1b0pP6/nt/C7C6D+beuFAK
-    SxfdVWnUiSWPuE7RfF3WXqECgYA14BhQlx216Fr7vcx/rlb8YAAgov1kbvqh51YF
-    MMuWIql80G/g+w+8UKFs5Uy+S+GDdU1/mM6plGcbSp946979huqCD8Q/OeqEp0nY
-    cuVfGHoPh31vV7/bbp5fkwUyw1s7lB4z/SmQ2ZAEcTT3PqzZ1xNlnkUfkZMDU7qU
-    a2x4kwKBgBfp02FxClAaT9hJZoa8SP9tgqNnXHg7rjT9J0AI9nsrLMAsopA/4+1/
-    7QfTOvaGJXlwidi2xtkujdLxP8Tg+EAe7VPOGx4GalAJ4lUynNjJjD6tC8Izlmkq
-    ZxLjjrJeuwM02PiSdxIGUCSlDqjy7H7qTZqenACN4fjImB87MJZ5
-    -----END RSA PRIVATE KEY-----
-- name: worker_cot_pubkey
-  path: /etc/taskcluster/secrets/worker_cot_pubkey
-  value: |
-    -----BEGIN PUBLIC KEY-----
-    MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwjwEarILpzMKeyAGibgw
-    V133FP8h/v72dElV0LWSOW/Ce3eMubIyfYq+w7pXnWL92Vnf4ieVTQFA0AHtx3WP
-    2YVfwRh/XXvhgNPJtlAHsKfEu/7lBQUsboF/dYvsS22UK5x0LG9Z0Mu+UQf3n0L/
-    7EnfFF9hlZDvAQ97usavsjP68omza0TNcMK1H6qpwLS6g5vALGV8gYZROjqzemuM
-    Pgo2of0tMebYwBRgInco/Oan64QtCIymAanBqrHVXf+vEfKkwNa1PH9mG3a3smeP
-    JKqR8Fy3q1w8xtkwLWbkfFxX+NmMpEWm2/BlbHPXnrU38ffmQJNzEUqKVS4Oy091
-    uwIDAQAB
-    -----END PUBLIC KEY-----
 # generated with: ssh-keygen -t ed25519
 - name: worker_ed25519_cot_key
   path: /etc/taskcluster/secrets/worker_ed25519_cot_key

scripts/docker-worker-linux/60-install-docker-worker.sh

@@ -60,7 +60,6 @@ worker:
     configPath: "${docker_worker_config}"
 # becomes part of docker-worker config
 workerConfig:
-    dockerWorkerPrivateKey: "${taskcluster_secrets_dir}/worker_cot_key"
     ed25519SigningKeyLocation: "${taskcluster_secrets_dir}/worker_ed25519_cot_key"
     ssl:
         certificate: "${taskcluster_secrets_dir}/worker_livelog_tls_cert"