rtmp-services: Always use CBR for all services

Services almost always recommend this be enabled, and I generally want
to make configuration easier for users; with CBR they don't have to set
things like the CRF value.

plugins/rtmp-services/data/services.json

@@ -109,7 +109,6 @@
         ],
         "recommended": {
             "keyint": 2,
-            "cbr": true,
             "profile": "main",
             "max video bitrate": 3500,
             "max audio bitrate": 160
@@ -129,7 +128,6 @@
         ],
         "recommended": {
             "keyint": 4,
-            "cbr": true,
             "profile": "main",
             "max video bitrate": 9000,
             "max audio bitrate": 160
@@ -209,7 +207,6 @@
         ],
         "recommended": {
             "keyint": 2,
-            "cbr": true,
             "profile": "main",
             "max video bitrate": 3500,
             "max audio bitrate": 160
@@ -311,7 +308,6 @@
             }
         ],
         "recommended": {
-            "cbr": true,
             "keyint": 2,
             "max audio bitrate": 160,
             "max video bitrate": 3500,