Remove redundant entries from docker config

* no_tls is now redundant (#4613)
* we don't need a dummy cert any more (#4618)

changelog.d/4619.misc

+Remove redundant entries from docker config

docker/conf/dummy.tls.crt

------BEGIN CERTIFICATE-----
-MIICnTCCAYUCAgPoMA0GCSqGSIb3DQEBCwUAMBQxEjAQBgNVBAMMCWxvY2FsaG9z
-dDAeFw0xOTAxMTUwMDQxNTBaFw0yOTAxMTIwMDQxNTBaMBQxEjAQBgNVBAMMCWxv
-Y2FsaG9zdDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMKqm81/8j5d
-R1s7VZ8ueg12gJrPVCCAOkp0UnuC/ZlXhN0HTvnhQ+B0IlSgB4CcQZyf4jnA6o4M
-rwSc7VX0MPE9x/idoA0g/0WoC6tsxugOrvbzCw8Tv+fnXglm6uVc7aFPfx69wU3q
-lUHGD/8jtEoHxmCG177Pt2lHAfiVLBAyMQGtETzxt/yAfkloaybe316qoljgK5WK
-cokdAt9G84EEqxNeEnx5FG3Vc100bAqJS4GvQlFgtF9KFEqZKEyB1yKBpPMDfPIS
-V9hIV0gswSmYI8dpyBlGf5lPElY68ZGABmOQgr0RI5qHK/h28OpFPE0q3v4AMHgZ
-I36wii4NrAUCAwEAATANBgkqhkiG9w0BAQsFAAOCAQEAfD8kcpZ+dn08xh1qtKtp
-X+/YNZaOBIeVdlCzfoZKNblSFAFD/jCfObNJYvZMUQ8NX2UtEJp1lTA6m7ltSsdY
-gpC2k1VD8iN+ooXklJmL0kxc7UUqho8I0l9vn35h+lhLF0ihT6XfZVi/lDHWl+4G
-rG+v9oxvCSCWrNWLearSlFPtQQ8xPtOE0nLwfXtOI/H/2kOuC38ihaIWM4jjbWXK
-E/ksgUfuDv0mFiwf1YdBF5/M3/qOowqzU8HgMJ3WoT/9Po5Ya1pWc+3BcxxytUDf
-XdMu0tWHKX84tZxLcR1nZHzluyvFFM8xNtLi9xV0Z7WbfT76V0C/ulEOybGInYsv
-nQ==
------END CERTIFICATE-----

docker/conf/homeserver.yaml

@@ -2,13 +2,7 @@
 
 ## TLS ##
 
-{% if SYNAPSE_NO_TLS %}
-no_tls: True
-
-# workaround for https://github.com/matrix-org/synapse/issues/4554
-tls_certificate_path: "/conf/dummy.tls.crt"
-
-{% else %}
+{% if not SYNAPSE_NO_TLS %}
 
 tls_certificate_path: "/data/{{ SYNAPSE_SERVER_NAME }}.tls.crt"
 tls_private_key_path: "/data/{{ SYNAPSE_SERVER_NAME }}.tls.key"