Markdown code block not interpreted as link text in 3.15.0

Description:

Steps to reproduce:

1. Update to RocketChat Version 3.15.0
2. Send a message with the following content or look for messages, that use this format :
   [```this is a code block that should also be used as a link```](http://www.thisisadomain.tld)

Expected behavior:

In the previous RocketChat versions the code block was a link. The actual link was hidden.
In GitHub it also works:
this is a code block that should also be used as a link

Actual behavior:

The code block isn't interpreted as the link text anymore.

Server Setup Information:

• Version of Rocket.Chat Server: 3.15.0
• Operating System: Debian 10.9
• Deployment Method: docker
• Number of Running Instances: 1
• DB Replicaset Oplog: ?
• NodeJS Version: v12.22.1
• MongoDB Version: 4.0

Client Setup Information

• Desktop App: 3.2.2
• Browser Version: Opera 76.0.4017.177
• Operating System: Pop!_OS 20.04 LTS

Additional context

Relevant logs:

Browser Log:

/api/ecdh_proxy/initEncryptedSession:1 Failed to load resource: the server responded with a status of 404 ()
/node_modules/@rocket.chat/ui-kit/dist/index.js:1 ui-kit version: 0.26.0
/node_modules/@rocket.chat/fuselage-ui-kit/dist/fuselage-ui-kit.production.js:1 fuselage-ui-kit version: 0.26.0
Henning:1 Failed to load resource: the server responded with a status of 404 ()

Server Log:

(node:8) [DEP0131] DeprecationWarning: The legacy HTTP parser is deprecated.
LocalStore: store created at 
LocalStore: store created at 
LocalStore: store created at 
Setting default file store to GridFS
{"line":"120","file":"migrations.js","message":"Migrations: Migrating from version 222 -> 225","time":{"$date":1622817733011},"level":"info"}
{"line":"120","file":"migrations.js","message":"Migrations: Running up() on version 223","time":{"$date":1622817733012},"level":"info"}
{"line":"120","file":"migrations.js","message":"Migrations: Running up() on version 224","time":{"$date":1622817733015},"level":"info"}
{"line":"120","file":"migrations.js","message":"Migrations: Running up() on version 225","time":{"$date":1622817733019},"level":"info"}
{"line":"120","file":"migrations.js","message":"Migrations: Finished migrating.","time":{"$date":1622817733051},"level":"info"}
Not migrating, control is locked. Attempt 1/30. Trying again in 10 seconds.
{"line":"120","file":"migrations.js","message":"Migrations: Not migrating, already at version 225","time":{"$date":1622817743062},"level":"info"}
ufs: temp directory created at "/tmp/ufs"
Loaded the Apps Framework and loaded a total of 0 Apps!
Using GridFS for custom sounds storage
Using GridFS for custom emoji storage
Updating process.env.MAIL_URL
➔ System ➔ startup
➔ +---------------------------------------------------------------+
➔ |                         SERVER RUNNING                        |
➔ +---------------------------------------------------------------+
➔ |                                                               |
➔ |  Rocket.Chat Version: 3.15.0                                  |
➔ |       NodeJS Version: 12.22.1 - x64                           |
➔ |      MongoDB Version: 4.0.24                                  |
➔ |       MongoDB Engine: mmapv1                                  |
➔ |             Platform: linux                                   |
➔ |         Process Port: 3000                                    |
➔ |             Site URL: https://**********/rocketchat/          |
➔ |     ReplicaSet OpLog: Enabled                                 |
➔ |          Commit Hash: 55457025d6                              |
➔ |        Commit Branch: HEAD                                    |
➔ |                                                               |
➔ +---------------------------------------------------------------+
(node:8) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.

Reproduce the issue in Rocket.Chat 3.15.0 with a Markdown code block used as link text, then trace the chat message rendering path that handles this syntax. Compare the rendered result with the expected linked code block and add coverage for the reported example; done means the code block remains the link text and the target URL is preserved.