minor #4667 Remove redundant "default" connection (xelaris)

This PR was merged into the 2.3 branch.

Discussion
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Remove redundant "default" connection

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | >=2.3
| Fixed tickets |

There where two connections with same key "default". I just removed the first one. It seems to be a relict from earlier versions.

Commits
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bab8f1a Remove redundant "default" connection.

Author: weaverryan

reference/configuration/doctrine.rst

@@ -26,9 +26,6 @@ Full Default Configuration
                 #schema_filter:        ^sf2_
 
                 connections:
-                    default:
-                        dbname:               database
-
                     # A collection of different named connections (e.g. default, conn2, etc)
                     default:
                         dbname:               ~